Chapter III: Part 3

_Type locality._--Rio 12 de Outubro, affluent of the Camararé,
_Mato Grosso_, Mato Grosso, Brazil; about 190 kilometers west of
Utiarití; altitude 414 meters. _Type_: Museu Nacional, no. 1935,
adult male (colors faded); collected on 20 June, 1909, by Prof. A.
Miranda Ribeiro; original number _G._

_Range._--Known only from the type locality.

_Diagnosis._--_Aristiforms wide and stiff_; incisive foramen small
and narrow; vomerine sheath complete and thick; p4 with four
counterfolds; remaining molariform teeth with three counterfolds.

_Pelage._--_Aristiforms on middorsal region_: Whitish basally,
gradually blackening toward tip; total length, 19 to 22 mm;
maximum width, 0.8 mm. _Setiforms on middorsal region_: Whitish on
basal half, gradually blackening toward tip but interrupted by
subapical zone probably of some tint of ochraceous; total length,
22 to 24 mm; maximum width, 0.06 mm. _Setiforms on outer thighs_:
Whitish basally, gradually blackening toward tip but interrupted
by probably light ochraceous, subapical zone; total length 14 to
16 mm; maximum width, 0.03 mm.

_Skull._--Slender; supraorbital ridges low; bullae ovate with
shallow grooves; postorbital process of zygoma almost obsolete and
involving mostly jugal; incisive foramen short and narrow (4 × 2
mm), constricted posteriorly and with posterior margins raised;
vomerine sheath complete and thick; mesopterygoid fossa extending
forward as far as posterior faces of second molars; posterior
palatine foramina on plane with centers of second molars.

_Teeth._--Upper molariform teeth with three counterfolds. Lower
molariform teeth: p4 with four counterfolds; molars with three
counterfolds which sometimes are fused.

_Comparisons._--From _P. g. bolivianus_, _ribeiroi_ differs in:
aristiforms wider; incisive foramen shorter and narrower; vomerine
sheath complete and thick, instead of complete or incomplete and
not thick; p4 always with four, instead of usually only three,
counterfolds and lower molars always with three, instead of
sometimes with only two, counterfolds in m3. Differences from _P.
g. villicauda_ are given in the account of that subspecies.

_Remarks._--The name _ribeiroi_ is given in honor of the late Professor Alipio Miranda Ribeiro, in recognition of his important work in Brazilian vertebrate zoology.

_Specimens examined._--Total number, 2 (MN), from Brazil, Mato
Grosso, _Mato Grosso_, Rio 12 de Outubro; altitude, 414 meters.

=Proechimys guyannensis hyleae= subspecies nova

_Type locality._--Tauarí, Rio Tapajoz, _Porto de Moz_, Pará,
Brazil; approximately 87 kilometers south of Santarem. _Type_:
Museum of Comparative Zoology at Harvard College, no. 30887, adult
male; collected on 19 January, 1934, by A. M. Olalla; original
number 7288.

_Range._--Region of lower Tapajoz River and banks of Amazon up to
the Jamundá River.

_Diagnosis._--Aristiforms conspicuously wide and stiff; general
color on upper parts Tawny; incisive foramen long and oval;
vomerine sheath complete but with maxillary part slender or,
sometimes, incomplete; p4 with four counterfolds, rarely three;
remaining molariform teeth with three counterfolds.

_Pelage._--_Aristiforms on middorsal region_: Whitish basally,
gradually becoming blackish toward tip; total length, 19 to 21 mm;
maximum width, 1.1 mm. _Setiforms on middorsal region_: a. Gray
basally, gradually blackening toward tip but interrupted by wide (5
to 6 mm) Tawny, subapical zone; some are whitish basally and
gradually become sooty brown toward tip except for same type of
subapical zone (tip only slightly darker than subapical zone); b.
With the same type described above and some completely blackish,
with the base gray; total length 22 to 25 mm; maximum width, 0.1
mm. _Setiforms on outer thighs_: Whitish basally, gradually
becoming gray and then blackish toward tip but interrupted by long,
Ochraceous-Tawny, subapical zone; tip, itself, blackish brown;
sometimes this type appears with some lighter ones and sometimes
with completely blackish setiforms; total length 16 to 18 mm;
maximum width 0.3 mm.

_Skull._--Medium in size and slender; cranium narrow and not
increasing much in breadth posteriorly; rostrum stout, laterally
thick, with masseteric crest well-developed; nasals pointed
posteriorly; supraorbital ridges broad but barely extended across
parietals; zygomatic arches strong; postorbital process of zygoma
involving mostly squamosal; incisive foramen long and narrow (5.5
to 6 × 2.5 mm), oval and extending posteriorly to point only 2 mm
anterior to premolars; vomerine sheath complete with maxillary
part usually slender; mesopterygoid fossa extending forward as far
as centers of third molars; bulla of medium size, well inflated
and with shallow grooves on surface.

_Teeth._--Upper molariform teeth with three counterfolds. Lower
premolar with four counterfolds or, sometimes (20 per cent of 15
specimens), with only three; lower molars with three counterfolds.

_Comparisons._--From _P. g. oris_ and _P. g. nesiotes_, _hyleae_
differs in: wider aristiforms; general color on upper parts Tawny,
instead of Ochraceous-Orange; vomerine sheath not always complete,
instead of always complete. From _P. g. oris_, _hyleae_ differs
in: p4 usually with four, instead of only three counterfolds and
all molars with three, instead of only lower molars with three
counterfolds. From _P. g. nesiotes_, _hyleae_ differs in: p4
usually, instead of always, with four counterfolds; color on back
Tawny instead of Ochraceous-Orange; aristiforms wider.

_Remarks._--This subspecies shows greater variability than any other in this species. There are two types of coloration. The most common type of coloration is dark, with Tawny, subapical zones in the setiforms of the middorsal region and many completely black setiforms; in the other type the subapical zone is still Tawny but there are no black setiforms. One specimen from Obidos, on the north bank of the Amazon, completely agrees in the characteristics of color and skull with the reddish type and suggests either that there is an extension of the range of the subspecies along the lower course of the Tapajoz or that there are two subspecies, in which event the animals from Tauarí are intergrades between _hyleae_ and an unnamed, tawny-colored subspecies occurring to the southward.

Between 13 and 23 January, 1934, A. M. Olalla collected 10 adult females, 6 of which contained embryos. Three of the females had 2 embryos each, two had 3 embryos each and one had only 1 embryo. At this same time and place only ten per cent of specimens obtained were not fully adult.

_Specimens examined._--Total number, 21, from Brazil, Pará, as
follows: _Porto de Moz_, Tauarí, right bank of Tapajoz,
approximately 85 kilometers south of Santarem, 20 (19 MCZ, 1 CNHM);
_Obidos_, Obidos, 1 (MCZ).

=Proechimys guyannensis nesiotes= subspecies nova

_Type locality._--Ilha de Manapirí, Rio Tocantins, Pará,
Brazil. _Type_: Chicago Natural History Museum, no. 19496, adult
male; collected on 9 December, 1910, by Dr. Emilia Snethlage;
original number, 12.

_Range._--Known only from the type locality.

_Diagnosis._--Aristiforms wide and stiff; general color on upper
parts Ochraceous-Orange; incisive foramen long, with parallel
borders; vomerine sheath complete and thick; p4 with four
counterfolds, remaining molariform teeth with three counterfolds.

_Pelage._--_Aristiforms on middorsal region_: Gray basally,
gradually blackening toward tip; total length, 18 to 19 mm;
maximum width, 0.9 mm. _Setiforms on middorsal region_: Gray
basally, gradually blackening toward tip but interrupted by
Ochraceous-Orange, subapical zone 4 mm long; total length 16 to 19
mm; maximum width, 0.06 mm. _Setiforms on outer thighs_: Whitish
basally, gradually becoming gray and blackish toward tip but
interrupted by Ochraceous-Buff, subapical zone 3 mm long; total
length, 13 to 15 mm; maximum width, 0.03 mm.

_Skull._--Of medium size; rostrum short; nasals pointed
posteriorly; postorbital ridges extending caudad across anterior
fifth of parietals; zygomatic arches strong; jugal with process in
posterior part of masseteric fossa; postorbital process of zygoma
involving mostly squamosal; incisive foramen elongate, narrow (5 x
2.3 mm), and parallel sided; posterior margin of incisive foramen
approximately 3 mm anterior to premolars; margins of foramen
raised to form ridges; vomerine sheath complete, of almost uniform
width and set deeply in foramen; mesopterygoid fossa extending
forward as far as centers of third molars; bullae of medium size
and inflated.

_Teeth._--Upper molariform teeth with three counterfolds; p4 with
four counterfolds; m1-3 with three counterfolds.

_Comparison._--_From P. g. oris_, _nesiotes_ differs in:
Aristiforms conspicuously wider; incisive foramen shorter and
narrower, with borders parallel instead of posteriorly
constricted; posterior margin of incisive foramen farther from
premolars; p4 with four, instead of three, counterfolds; lower
molars with three instead of two counterfolds. From _P. g.
leioprimna_, _nesiotes_ differs in: Incisive foramen with parallel
borders instead of oval; p4 with four instead of three
counterfolds; m3 always with three instead of two counterfolds.

_Remarks._--Dr. E. Snethlage mentions the type as having been collected at night in the forest.

_Specimens examined._--Total number, 8 (MCZ, CNHM, MN), from
Brazil, Pará, Tocantins River, Ilha de Manapirí.

=Proechimys guyannensis leioprimna= subspecies nova

_Type locality._--Cametá, left bank of Tocantins River, near its
mouth, Cametá, Pará, Brazil. _Type_: Chicago Natural History
Museum, no. 19503, adult female; collected on 21 January, 1911, by
Dr. Emilia Snethlage; original number, 35.

_Range._--Known only from type locality but probably extending
westward toward Xingú River.

_Diagnosis._--Aristiforms wide and stiff; general color on upper
parts Ochraceous-Orange, incisive foramen moderately long; oval;
vomerine sheath complete; all molariform teeth with three
counterfolds, except lower, third molar which has only two.

_Pelage._--_Aristiforms on middorsal region_: Gray basally,
gradually blackening toward tip which is extended as a short
filament; total length, 19 to 21 mm; maximum width, 0.8 to 1 mm.
_Setiforms on middorsal region_: Whitish basally, gradually
blackening toward tip but interrupted by Ochraceous-Orange,
subapical zone 2 to 3 mm long; total length, 17 to 20 mm; maximum
width 0.1 mm. _Setiforms on outer thighs_: Whitish basally,
becoming gradually gray and then blackish toward tip but
interrupted by Ochraceous-Buff, subapical zone; blackish tip
short; total length 13 to 15 mm; maximum width 0.06 mm.

_Skull._--Of medium size; rostrum relatively short; nasals with
posterior borders rounded; postorbital ridges extending across
anterior fourth of parietals; zygomatic arches moderately strong;
postorbital process of zygoma involving both jugal and squamosal;
incisive foramen of medium length (4 to 5 mm) and narrow (about
2.5 mm), oval and extending caudad to a plane approximately 2 mm
anterior to premolars; vomerine sheath complete, with premaxillae
forming approximately anterior 3/4 of sheath; maxillary part of
sheath short but well-developed; mesopterygoid fossa extending
forward as far as centers of third molars; bullae of medium size
but well-inflated.

_Teeth._--Upper molariform teeth with three counterfolds. Lower
molariform teeth with three counterfolds, except third molar which
has only two.

_Comparison._--From _P. g. oris_, _leioprimna_ differs in:
conspicuously wider aristiforms; shorter and narrower incisive
foramen; lower molariform teeth with three counterfolds (except m3
with only two), instead of lower molars with only two
counterfolds. Differences from _P. g. nesiotes_ are given in the
account of that subspecies.

_Remarks._--The paratype was collected in an "igarapé," depression usually invaded by the river waters; the paratype, collected on 18 January, 1911, had two large embryos.

_Specimens examined._--Total number, 4 (2 CNHM, 2 AMNH), from
Brazil, Pará, Cametá.

=Proechimys guyannensis oris= Thomas

_Proechimys oris_ Thomas, September, 1904, Ann. Mag. Nat. Hist., 14
(ser. 7): 195; Thomas, 1905, Ann. Mag. Nat. Hist., 15 (ser. 7):587;
Thomas, 1912, Ann. Mag. Nat. Hist., 9 (ser. 8):89; Tate, 1935,
Bull. Amer. Mus. Nat. Hist., 68:400; Osgood, 1944, Zool. Ser. Field
Mus. Nat. Hist., 29:199.

_Proechimys cayennensis oris_ Ellerman, 1940, The families and
genera of living rodents, Brit. Mus. (Nat. Hist.), 1:121.

_Type locality._--Igarapé-assú, E. F. B., near Belem, Igarapé-assú,
Pará, Brazil. _Type_: British Museum (Nat. Hist.), no. 4.7.4.78,
old male; collected on 6 March, 1904, by Alphonse Robert; original
number, 1818.

_Range._--Probably most of the region on south bank of Amazon
River, between Tocantins (west) and Gurupí River (south).

_Diagnosis._--Aristiforms narrow but somewhat stiff; color on
upper parts Ochraceous-Orange; incisive foramen long and wide,
conspicuously constricted posteriorly; posterior margin of incisive
foramen close to plane of premolars; vomerine sheath complete but
maxillary part threadlike; upper molariform teeth and lower
premolar with three counterfolds; lower molars with only two
counterfolds.

_Pelage._--_Aristiforms on middorsal region_: Gray basally,
gradually blackening toward tip, which is extended as a filament;
total length, 16 to 17 mm; maximum width, 0.6 to 0.7 mm.
_Setiforms on middorsal region_: Gray basally, gradually becoming
blackish toward tip but interrupted by Ochraceous-Orange,
subapical zone 2 to 4 mm long; total length, 18 to 20 mm; maximum
width 0.06 mm. _Setiforms on outer thighs_: Whitish basally,
gradually becoming blackish toward tip but interrupted by
Ochraceous-Buff, subapical zone; total length, 15 to 16 mm;
maximum width, 0.04 mm.

_Skull._--Of medium size; supraorbital ridges well developed and
extending across anterior fifth of parietals; zygomatic arches
strong; jugal with masseteric fossa deep and with well-developed
posterior process; postorbital zygomatic process involving mostly
squamosal; incisive foramen long (6 to 7 mm), widest anteriorly
(2.5 to 3.2 mm); but narrowing posteriorly to less than 1 mm and
extending caudad almost to plane of premolars; vomerine sheath
complete but maxillary part delicate and threadlike; mesopterygoid
fossa extending forward as far as third molars or posterior parts
of second molars; bullae large and inflated.

_Teeth._--Each upper molariform tooth with three counterfolds. In
lower jaw, premolar with three, and molars with only two,
counterfolds.

_Comparisons._--Differences from the subspecies with adjoining
ranges are given in the accounts of those subspecies.

_Remarks._--Thomas (1912:89) extended the known range of the subspecies to Faro, on the Jamundá River, on the left bank of the Amazon, and to Boim, on the Tapajoz River, as well as to Benevides, E. F. Braganca, near Belem. It seems to me that the specimens from Faro should be referred provisionally to _Proechimys guyannensis hyleae_; the specimens from Boim are "more brightly rufous" (Thomas, _loc. cit._) and could be referred to Allen's _P. boimensis_, described in 1914, but _P. guyannensis hyleae_ probably lives in the same place and only an examination of the specimens, which I have not seen, would permit of certainly allocating the specimens to their correct species. The specimens from Benevides are more certainly _P. g. oris_.

E. Snethlage collected one specimen in a garden (Providencia, E. F. B.). However, according to the personnel of the Brazilian Health Service, the animals are strictly forest dwellers although they do make excursions into more open places.

_Specimens examined._--Total number, 3, from Brazil, Pará, as
follows: Providencia, E. F. B., approximately 15 kilometers east
from Belem, 1 (CNHM); Tanaquará, near Belem, 1 (MN); Rio Guamá,
near Belem, 1 (AMNH).

_Additional record._--Brazil, Pará, Benevides, E. F. B.,
approximately 100 kilometers north-east of Belem (Thomas,
1912:89).

=Proechimys guyannensis arescens= Osgood

_Proechimys cayennensis arescens_ Osgood, 12 July 1944, Zool. Ser.
Field Mus. Nat. Hist., 29(13): 198.

_Type locality._--Fazenda Inhuma, below Santa Filomena, upper Rio
Parnaiba, _Vitoria do Alto Parnaiba_, Maranhão, Brazil. _Type_:
Chicago Natural History Museum, no. 26441, adult male; collected on
5 August, 1925, by Heinrich E. Snethlage.

_Range._--Region including the valleys of the Turí-assú and
Parnaiba rivers, Maranhão, Brazil.

_Diagnosis._--Aristiforms moderately wide and not conspicuously
stiff; general color of upper parts near (15'a) Ochraceous-Orange;
incisive foramen long and wide; vomerine sheath complete or
incomplete; upper molariform teeth and lower premolar with three
counterfolds; lower molars with only two.

_Pelage._--_Aristiforms on middorsal region_: Whitish basally,
gradually blackening toward tip; total length, 19 to 21 mm;
maximum width, 0.7 mm. _Setiforms on middorsal region_: Whitish
basally or on basal half, gradually becoming gray and then
blackish toward tip, but interrupted by long (5 to 6 mm) subapical
zone near (15'_a_) Ochraceous-Orange; total length, 15 to 16 mm;
maximum width 0.05 mm. _Setiforms on outer thighs_: Whitish on
basal half, gradually becoming gray and then blackish toward tip
but interrupted by Ochraceous-Buff, subapical zone; tip sometimes
not conspicuously darker than subapical zone; total length 18 to
25 mm; maximum width, 0.03 mm.

_Skull._--Medium in size, not elongated; nasals pointed
posteriorly; supraorbital ridges strong and thick, extending
caudad across anterior third of parietals; zygomatic arches
strong; postorbital process of zygoma involving only squamosal;
incisive foramen 5 by 2.7 mm, oval and extending caudad to plane
approximately 2 mm anterior to premolars; posterior margins of
incisive foramen not forming a ridge; vomerine sheath complete and
with maxillary part slender and threadlike, or incomplete, in
which event, maxillary part not extended enough to join
premaxillary process; mesopterygoid fossa extending forward
as far as centers of third molars; bulla large and more or less
triangular in its peripheral outline.

_Teeth._--Upper molariform teeth with three counterfolds each.
Lower premolar with three counterfolds; lower molars with two
counterfolds.

_Comparisons._--From _P. g. oris_, _arescens_ differs in: Color of
upper parts lighter and more uniform; incisive foramen oval
instead of conspicuously constricted posteriorly; posterior margin
of incisive foramen farther from premolars.

_Remarks._--One specimen from Turí-assú (MN) has been identified by O. Thomas as "_P. oris_" (his own handwriting is on the label) and the subspecies is really closely related to _oris_.

_Specimens examined._--Total number, 3, from Brazil, Maranhão, as
follows: _Vitoria do Alto Parnaiba_, Fazenda Inhuma (below Santa
Filomena), 2 (CNHM); Alto da Alegria, Turí-assú, 1 (MN).

=Proechimys guyannensis riparum= subspecies nova

_Type locality._--Manaus, _Manaus_, Amazonas, Brazil. _Type_:
American Museum of Natural History, no. 143018, adult female;
collected 6 March, 1943.

_Range._--Known only from type locality but probably extending
northward and eastward.

_Diagnosis._--Aristiforms wide and stiff; upper parts
Ochraceous-Tawny; incisive foramen short, wide, and oval; vomerine
sheath incomplete; upper molariform teeth and lower premolar with
three counterfolds; lower molars with only two counterfolds.

_Pelage._--_Aristiforms on middorsal region_: Gray basally
gradually blackening toward tip; total length, 18 to 20 mm;
maximum width, 0.9 mm. _Setiforms on middorsal region_: Whitish
basally, gradually blackening toward tip but interrupted by 2 mm
long, Ochraceous-Tawny, subapical zone; total length 20 to 22 mm;
maximum width, 0.04 mm. Some are whitish basally and gradually
become black toward tip with no subapical zone. _Setiforms on
outer thighs_: Whitish basally, gradually becoming gray and then
blackish toward tip but interrupted by Ochraceous-Buff, subapical
zone 3 to 4 mm long; tip not conspicuously dark; total length, 17
to 19 mm; maximum width, 0.03 mm.

_Skull._--Of medium size and slender; rostrum slender; nasals
rounded posteriorly; supraorbital ridges well developed and barely
extended onto anteriormost part of parietals; zygomatic arches
slender; infraorbital foramen with well-developed groove for nerve
transmission; postorbital process of zygoma almost obsolete and
involving mostly squamosal; incisive foramen short and wide (4.5 ×
3.3 mm), oval and with posterior margins raised to form ridges
which extend toward premolars; posterior margin of incisive
foramen approximately 2.5 mm anterior to premolars; vomerine
sheath incomplete, with only short, premaxillary part;
mesopterygoid fossa extending forward as far as anterior
parts of third molars; bullae large and inflated, with more or
less triangular outline.

_Teeth._--Crown length of well worn P4-M3, 6.8 mm; upper
molariform teeth with three counterfolds each. Lower premolar
with three counterfolds; lower molars with two counterfolds.

_Comparisons._--From _P. g. oris_ and _P. g. hyleae_, _riparum_
differs in: Shorter and wider incisive foramen; vomerine sheath
incomplete, instead of sometimes incomplete. From _P. g. oris_,
_riparum_ differs in: Upper parts Ochraceous-Tawny instead of
Ochraceous-Orange; aristiforms conspicuously wider. From _P. g.
hyleae_, _riparum_ differs in: Aristiforms narrower; upper parts
Ochraceous-Tawny instead of Tawny; lower premolars with three,
instead of four, counterfolds; lower molars with two, instead of
three, counterfolds.

_Specimens examined._--Type only.

=Proechimys guyannensis arabupu= subspecies nova

_Type locality._--Arabupu, Mount Roraima, _Bõa Vista_, Territ. Rio
Branco; about 1540 meters altitude. _Type_: American Museum of
Natural History, no. 75816, adult male; collected by Dr. G. H. H.
Tate on 30 December, 1927; original number, 4716.

_Range._--Known only from the type locality.

_Diagnosis._--Aristiforms conspicuously wide and stiff; color on
upper parts dark, near (15'_j_) Ochraceous-Tawny; incisive foramen
widest in anterior third; vomerine sheath complete, sometimes
incomplete; upper molariform teeth and lower premolar with three
counterfolds; lower molars with two counterfolds.

_Pelage._--_Aristiforms on middorsal region_: Whitish basally,
gradually blackening toward tip; total length, 19 to 22 mm;
maximum width, 1.1 mm. _Setiforms on middorsal region_: Gray
basally, gradually blackening toward tip but interrupted by dark
(15'j) Ochraceous-Tawny, subapical zone 3 mm long; some completely
blackish on distal parts; total length, 20 to 23 mm; maximum
width, 0.07. _Setiforms on outer thighs_: Whitish basally,
gradually blackening toward tip but interrupted by Ochraceous-Buff
or Light Ochraceous-Buff, subapical zone; total length, 20 to 23
mm; maximum width, 0.07 mm.

_Skull._--Size medium; nasals pointed posteriorly; supraorbital
ridges prominent and slightly extended caudad onto anterior half
of parietals; groove for transmission of nerve in infraorbital
foramen weakly developed; zygomatic arches strong; postorbital
process of zygoma involving mostly squamosal; incisive foramen
approximately 5.5 × 2.7 mm, widest in anterior third and
constricted posteriorly, with posterior margin about 1 mm anterior
to plane of premolars; vomerine sheath complete, with premaxillary
part expanded and maxillary part notably slender and sometimes
lacking; mesopterygoid fossa in some specimens extending forward
as far as middle parts of second molars; bullae large and
inflated.

_Teeth._--Upper molariform teeth with three counterfolds each.
Lower premolar with three counterfolds; molars with only two.

_Comparisons._--From _P. g. warreni_, _arabupu_ differs in:
Narrower aristiforms; narrower incisive foramen; lower premolar
with three instead of four counterfolds; lower molars with two,
instead of three, counterfolds. From _P. g. oris_, _arabupu_
differs in: Aristiforms wider; posterior margin of incisive
foramen farther from plane of premolars; upper parts dark (15'_j_)
Ochraceous-Tawny, instead of Ochraceous-Orange.

_Remarks._--The sample is fairly uniform.

_Specimens examined._--Total number, 6 (AMNH), from Brazil,
Territorio do Rio Branco, Bõa Vista, Mount Roraima, Arabupu;
approximately 1540 m. altitude.

Subgenus =TRINOMYS= Thomas

_Genotype._--_Echimys albispinus_ Is. Geoffroy Saint-Hilaire, 1838;
by original designation.

_Trinomys_ Thomas, July 1921, Ann. Mag. Nat. Hist., 8 (ser. 9):140
(orig. descr.); Tate, 1935, Bull. Amer. Mus. Nat. Hist.,
68(5):401; Ellerman, 1940, The families and genera of living
rodents, Brit. Mus. (Nat. Hist.), 1:115.

_General characters._--Pelage of upper parts with lanceolate and,
sometimes, clavate aristiforms extending over most of rump and onto
thighs; tail 86 to 103 per cent of length of head and body; tail
sometimes white-tipped and sometimes penicillate; skull small, with
ridges moderately developed; supraorbital ridges involving no part
of parietals; infraorbital foramen with no separate groove for
transmission of nerve; mesopterygoid fossa extending forward to
level of second or first molars; incisors opisthodont, orthodont or
proodont; molariform teeth, in occlusal view, with main fold large
and usually reaching opposite wall; no counterfold anterior to main
fold in upper molariform teeth and usually no counterfold posterior
to main fold in lower molariform teeth; premolars larger than first
molars, first molars larger than second molars and second molars
larger than third molars; four molariform teeth of nearly equal
size in some animals.

Thomas (1921:140) erected the subgenus _Trinomys_, including in it
the species _albispinus_ and _setosus_ and stated that "the primary
distinction between these [_Trinomys_ and _Proechimys_] lies in the
number of laminae present in the cheekteeth--four in _Proechimys_,
three in _Trinomys_." The distinction is valueless as a subgeneric
character, not only because the character is not constant in the
species in the subgenus but also because there is subspecific
variation in number of laminae in the cheekteeth. _Proechimys
albispinus_, however, shares with three other species common
characters, as listed above, and the name _Trinomys_ will,
therefore, apply to this group of species, since _Proechimys
albispinus_ is the genotype.

=Proechimys dimidiatus= (Günther)

_Echimys dimidiatus_ Günther, 1 April 1877, Proc. Zool. Soc.
London, 1876(4):747.

_Proechimys dimidiatus_ Allen, 1899, Bull. Amer. Mus. Nat. Hist.,
12(20):264; Ribeiro, 1905, Arch. Mus. Nac. Rio de Janeiro, 13:187;
Thomas, 1921, Ann. Mag. Nat. Hist., 8 (ser. 9):141; Tate, 1935,
Bull. Amer. Mus. Nat. Hist., 68(5):400; Ellerman, 1940, The
families and genera of living rodents, Brit. Mus. (Nat. Hist.),
1:122.

_Type locality._--Unknown; probably southwestern Rio de Janeiro,
Brazil (see Remarks). _Type_: British Museum (Nat. Hist.), no.
51.7.21.24; presented by Lord Derby.

_Range._--Rio de Janeiro, from the southern limit of the state
northward to and including the Distrito Federal.

_General characters._--Size large; tail averaging 80 per cent of
head and body; aristiforms narrow and soft (0.4 to 0.5 mm wide),
imparting a non-spiny character to the pelage; general color of
upper parts Ochraceous-Buff, finely lined with blackish brown,
gradually becoming lighter on sides; ventral surface of body and
inner sides of legs white; feet dorsally white but with a
sepia-colored stripe along outer margin; tail brownish-black above
and white below, but white sometimes extended to upper side in
distal part; skull broad with no conspicuous ridges; jugals deep
with transverse ridge usually conspicuous; postorbital process of
zygoma involving only squamosal; incisive foramen short and wide
posteriorly; vomerine sheath complete in 95 per cent of specimens
and with maxillary part thick; posterior palatine foramina at
plane of first molars or slightly anterior to them; bullae
moderately developed; in juvenal specimens, each upper molariform
tooth with three counterfolds, but posteriormost counterfold
small; in adult specimens, posteriormost counterfold
disappearing in 50 per cent of fourth premolars and first molars,
in 20 per cent of second molars, and in 15 per cent of third
molars; lower molariform teeth with two counterfolds in almost
every juvenal specimen, this number, in adult animals, decreasing
in m3 to one in 20 per cent of specimens but rarely being reduced
in other teeth.

_General characters._--Aristiforms soft and narrow, ranging from 15
to 19 mm in total length and 0.4 to 0.5 mm in maximum width; pelage
generally non-spiny and not harsh; length of tail ranging from 20
per cent shorter than head and body to as long as, or slightly
longer than, head and body; ears rather small (23 to 25 mm).

_Color._--General color of back and sides results from uniform
mixture of black distal parts of aristiforms with Ochraceous-Buff
of subapical zone of setiforms. Dorsally, from nose caudad to rump,
mixture appears brownish-black, lined with Ochraceous-Buff; toward
sides, amount of Ochraceous-Buff gradually increases and resultant
color is much lighter brown than on back. On outer parts of arms
and legs, color turns gradually to sepia toward distal parts and
finally to uniform sepia on wrists and ankles, this color extending
to outer dorsal parts of hands and feet; on ankles, sepia forms
complete ring, as usual in the genus. Tail blackish-brown on upper
parts, this stripe gradually tapering toward tip where dark brown
hairs form small pencil; white of under side of tail sometimes seen
also entirely around distal part, short of tip which remains dark
brown. Ventral surfaces wholly white, from upper lips caudad
including inner surfaces of legs.

_Hairs._--_Aristiforms on middorsal region_: Gray basally,
gradually blackening toward tip that has long, fine filament;
total length 16 to 19 mm; maximum width 0.5 mm. On outer thigh
whitish basally, gradually blackening toward tip; some with
Ochraceous-Buff, subapical zone; total length 13 to
15 mm; maximum width 0.25 mm. _Setiforms on middorsal region_:
Whitish on basal half, gradually blackening toward tip, but
interrupted by Ochraceous-Buff, subapical zone; some with Light
Ochraceous-Buff, subapical zone and short, blackish zone on tip;
total length 12 to 14 mm; maximum width 0.02 mm. _Setiforms on
outer thighs_: Whitish on basal half, then gradually becoming gray
on middle part and finally Light Ochraceous-Buff on distal third,
or with tip blackish and Ochraceous-Buff, subapical zone.

_Skull._--Elongate and broad with no conspicuous crests; rostrum
rather stout; jugals deep with transverse crest usually
well-developed; zygomatic postorbital process conspicuous and
formed entirely of squamosal; incisive foramen short and wide
posteriorly; vomerine sheath complete in great majority of
specimens, its maxillary part wide and strong; posterior palatine
foramina on plane with front of M1 or slightly farther forward;
bullae rather small and elongate.

_Teeth._--P4 with three secondary folds in all juvenal specimens,
but posteriormost fold small and disappearing in 50 per cent of
adult specimens; M1 with 3 outer folds in juveniles and also
disappearing in 50 per cent of adults; M2 with three outer folds
in juveniles, but only 20 per cent remaining in adults; M3 with 3
outer folds in 50 per cent of juveniles, decreasing to 15 per cent
in adults. Lower molariform teeth: p4 with 2 secondary folds; m1
with 2 secondary folds in 90 per cent of adults and in all
juveniles; m2 with 2 secondary folds in 98 per cent of adults and
in all juveniles; m3 with 2 secondary folds in 81 per cent of
adults, remaining percentage with only one counterfold, and with 2
secondary folds in all juveniles.

_Remarks._--Samples studied of _P. dimidiatus_ are notably uniform throughout the geographic range of the species. The few biotypes detected seemed unworthy of subspecific rank.

In discussing the type locality of the species, Thomas (1921:141) states: "We know that its donor did obtain a number of specimens from Rio Janeiro, and the skull agrees so closely with those of two examples from Itatiaia, near to the Rio-Minas frontier, collected and presented by Prof. J. P. Hill, that I have no hesitation in referring the latter to Günther's species."

_Specimens examined._--Total number, 211 (MN), from Brazil as
follows: Rio de Janeiro; _Parati_, Pedra Branca (400 m.), 113;
_Mangaratiba_, Fazenda do Rubião (750 m.), 3; Fazenda do Tenente
(700 m.), 4; Fazenda da Lapa (450 m.), 13; _Teresópolis_, Fazenda
Guinle (960 m.), 61; _Nova Iguassú_, Barro Branco (20 m.), 16;
Distrito Federal, Tijuca, 1.

_Additional records._--Rio de Janeiro, Itatiaia (Thomas,
1921:141); Rio de Janeiro, Zona da mata, Mont-Serrat, Serra do
Itatiaia (Ribeiro, 1905:187).

=Proechimys iheringi= Thomas

_General characters._--Size large; tail long; aristiforms generally
wide and stiff; general color on upper parts and sides a
combination of blackish from tips of aristiforms with cinnamon
ground color from subapical zones of setiforms; darker band on
middorsal line; differentiated light-colored aristiforms
conspicuous on outer sides of thighs and rump; usually rufous tint
on neck and postauricular region; underparts white; tail with white
tip, usually accentuated by white brush; feet white on dorsal
surface; hind feet slightly darker on outer sides; skull elongate
and smooth; jugals wide dorso-ventrally; incisive foramen elongate;
upper molariform teeth usually with one to five counterfolds, number
varying with subspecies; lower premolar always with two counterfolds
and lower molars always with one or two counterfolds.

_Remarks._--As a whole, the samples of the populations of the species do not afford a satisfactory record of the distribution; my concept of the group may be changed when further collections are made in localities geographically intermediate between those from which specimens now are known. If some of the forms prove to be physiologically isolated, they may deserve treatment as full species according to the conventional standards of systematic zoology. _P. panema_, for example, does not seem to be geographically isolated from _P. gratiosus_. _P. denigratus_, at the northernmost known occurrence of the species, actually represents a striking jump in the cline, although collections from intermediate regions may provide intermediate structural stages. Further collecting may also prove that the southern form, _P. iheringi iheringi_, is completely isolated from the rest of the group. However, these samples are certainly more related to each other than any one of them is to that of the other species found in the same range, namely _P. dimidiatus_, and all the forms in question, therefore, seem best arranged as subspecies of one full species. A clinal variation certainly exists among these forms and the most striking differences correspond to larger geographical distances.

=Proechimys iheringi iheringi= Thomas

_Proechimys iheringi_ Thomas, August, 1911, Ann. Mag. Nat. Hist., 8
(ser. 8):252 (orig. descr.); Thomas, 1921, Ann. Mag. Nat. Hist., 8
(ser. 9):141; Tate, 1935, Bull. Amer. Mus. Nat. Hist., 68(5):400;
Ellerman, 1940, The families and genera of living rodents, Brit.
Mus. (Nat. Hist.), 1:122.

_Type locality._--Island of São Sebastião (off São Paulo), Formosa,
São Paulo, Brazil. _Type_: British Museum (Nat. Hist.), no.
2.8.25.5, adult male, presented by the São Paulo Museum.

_Range._--Littoral and islands of São Paulo and Rio de Janeiro.

_Diagnosis._--Aristiforms narrow; tail shorter than head and body;
setiforms Cinnamon-Buff; incisive foramen short; vomerine sheath
complete; upper molariform teeth with two or three counterfolds;
lower molariform teeth with two counterfolds, rarely one in m3.

_Pelage._--_Aristiforms on middorsal region_: Gray basally,
gradually blackening toward tip; total length 18 to 23 mm; maximum
width, 0.6 mm. _Aristiforms on outer thighs_: Gray basally,
blackening distally toward tip; some differentiated with
Cinnamon-Buff tip. _Setiforms on middorsal region_: Gray basally,
gradually blackening toward tip but interrupted by a
Cinnamon-Buff, subapical zone 3 mm long; total length, 16 to 20
mm; maximum width, 0.06 mm. _Setiforms on outer thighs_: Gray
basally, gradually blackening toward tip but interrupted by
Cinnamon-Buff, subapical zone or with Cinnamon-Buff continuous to
tip.

_Skull._--Slender; bullae small and well inflated; jugal
dorso-ventrally wide with transverse ridge inconspicuous; incisive
foramen short, 3.5 × 2.5 mm; vomerine sheath complete;
mesopterygoid fossa extending forward as far as middle parts of
second molars; postorbital process of zygoma small, formed by both
jugal and squamosal; posterior palatine foramina at plane of
premolars; interorbital breadth narrow.

_Teeth._--Upper molariform teeth with two or three counterfolds
(when unworn usually three and rarely four); sometimes only one
counterfold in M3 and sometimes counterfolds fused in molars.
Lower molariform teeth with two counterfolds, rarely one in m3.

_Comparisons._--From _P. i. bonafidei_ and _P. i. gratiosus_,
_iheringi_ differs in: Incisive foramen shorter; vomerine sheath
complete, instead of usually incomplete; setiforms Cinnamon-Buff,
instead of Ochraceous-Buff; upper molariform teeth with two or
three separate counterfolds, instead of having counterfolds fused
or reduced to one or two; aristiforms narrower in _iheringi_ than
in _bonafidei_.

_Specimens examined._--Total number, 25, from Brazil, as follows:
São Paulo, _Formosa_, Ilha de São Sebastião, 9 (DZ 6, MN 2, MCZ 1);
São Paulo, _Mogi das Cruzes_, Alto da Serra, alt. 900 m., 2 (DZ);
São Paulo, _Ubatuba_, alt. 10 m., 4 (2 DZ, 2 MN); Rio de Janeiro,
_Angra dos Reis_, 2 (MN); Rio de Janeiro, _Angra dos Reis_, Ilha
Grande, 7 (5 DZ, 1 MCZ, 1 MN).

=Proechimys iheringi bonafidei= subspecies nova

_Type locality._--Fazenda Bõa Fé, _Teresópolis_, Rio de Janeiro,
Brazil; alt. 850 meters. _Type_: Museu Nacional, no. 6183, adult
male; collected on 18 August, 1942, by G. Pereira; SEPFA no. M
14663.

_Range._--Known only from the type locality.

_Diagnosis._--Aristiforms wide and stiff; tail shorter than head
and body; setiforms Ochraceous-Buff; incisive foramen long;
vomerine sheath incomplete, or rarely complete; molariform teeth
with two counterfolds usually fused.

_Pelage._--_Aristiforms on middorsal region_: Gray basally,
gradually blackening toward tip; total length, 22 to 26 mm;
maximum width, 0.8 mm. _Aristiforms on outer thighs_: Gray
basally, gradually blackening toward tip but interrupted by
Ochraceous-Buff subapical zone; some Ochraceous-Buff to tip; total
length, 18 to 20 mm; maximum width, 0.7 mm. _Setiforms on
middorsal region_: Gray basally, gradually blackening toward tip
but interrupted by Ochraceous-Buff, subapical zone; total length,
17 to 20 mm; maximum width, 0.06 mm. _Setiforms on outer thighs_:
Gray basally, gradually blackening toward tip but interrupted by
Ochraceous-Buff, subapical zone; only a short blackened tip.

_Skull._--Large, with elongate rostrum; bullae large and well
inflated; jugals with transverse ridge inconspicuous; postorbital
process of zygoma small, formed mostly by squamosal; incisive
foramen elongated (5.5 × 2.5 mm); vomerine sheath incomplete or,
if complete, with maxillary part thin and delicate; posterior
palatine foramen at plane of first molars; mesopterygoid fossa
extending forward as far as middle parts of second molars.

_Teeth._--Upper molariform teeth with two counterfolds; these
completely separated in 3 of 16 specimens; two counterfolds
coalesced in all three molars in 6 specimens; counterfolds
coalesced in only two molars in 3 specimens; counterfolds
coalesced in only one molar in 4 specimens. Lower molariform teeth
with two counterfolds which are completely separated in 13 of 16
specimens; counterfolds coalesced in only one molar in 2
specimens; counterfolds coalesced in all three molars in one
specimen.

_Comparisons._--From _P. i. gratiosus_, _bonafidei_ differs in:
Aristiforms wider; tail shorter; molariform teeth with two
counterfolds instead of one or two. Differences from _P. i.
iheringi_ are given in the account of that subspecies.

_Remarks._--Of females with embryos two were captured in April and one in September. The embryos number 2, 1, 2. Young were captured mostly in April, but two were taken in July. Male gonads seemed to be most active in March, April and September. The animals lived in a second growth forest, approaching the climax. The rainfall was more than 1600 mm annually, and the mean annual temperature was 18.5° centigrade.

_Specimens examined._--Total number, 18 (MN), from Brazil, Rio de
Janeiro, _Teresópolis_, Fazenda Bõa Fé.

=Proechimys iheringi gratiosus= subspecies nova

_Type locality._--Floresta da Caixa Dagua, _Santa Teresa_, Espirito
Santo, Brazil; altitude 750 meters. _Type_: Museu Nacional, no.
4024, adult male; collected on 25 May, 1940, by C. Lako; SEPFA no.
M 6911.

_Range._--Known only from the type locality.

_Diagnosis._--Aristiforms narrow; tail of same length as head and
body; setiforms Ochraceous-Buff; incisive foramen long; vomerine
sheath usually incomplete; upper molariform teeth with one or two
counterfolds; lower molariform teeth with two counterfolds, except
that m3 usually has only one.

_Pelage._--_Aristiforms on middorsal region_: Gray basally,
gradually blackening toward tip; total length, 21 to 27 mm; maximum
width, 0.6 mm. _Aristiforms on outer thighs_: Gray basally,
gradually blackening toward middle, and Ochraceous-Buff on distal
half; total length, 18 to 21 mm; maximum width, 0.5 mm. _Setiforms
on middorsal region_: Gray basally, gradually blackening toward tip
but interrupted by short, Ochraceous-Buff, subapical zone; total
length, 18 to 20 mm; maximum width, 0.06 mm. _Setiforms on outer
thighs_: Gray basally, gradually blackening toward middle, and
distal part Ochraceous-Buff or with only tip blackened; total
length, 14 to 16 mm; maximum width, 0.05 mm.

_Skull._--Slender; bullae small but well-inflated; upper edge of
jugals deeply concave; transverse ridge of jugals conspicuous;
postorbital process of zygoma small, involving only squamosal;
incisive foramen elongate (5 x 2.5 mm); vomerine sheath almost
always incomplete, and maxillary part lacking or, when present,
slender; mesopterygoid fossa extending forward as far as middle of
second molars; posterior palatine foramina at plane of front
border of first molars or slightly anterior thereto.

_Teeth._--Upper molariform teeth with two counterfolds in 10 of 16
specimens and only one in remainder; these folds commonly
coalesced; M3 with only one counterfold in 6 specimens, and 2
counterfolds in remainder. Lower molariform teeth with two
counterfolds in 6 specimens and in 10 of them m3 has only one
counterfold.

_Comparisons._--From _P. i. panema_, _gratiosus_ differs in: Lower
molariform teeth with only one counterfold in smaller percentage
of specimens; incisive foramen shorter; aristiforms narrower;
setiforms Ochraceous-Buff instead of Cinnamon. Differences from
_iheringi_ and _paratus_ are given in the accounts of those
subspecies.

_Remarks._--All the animals were captured in climax forest.

_Specimens examined._--Total number, 16 (MN), from Brazil, Espirito
Santo, _Santa Teresa_, Floresta da Caixa Dagua, altitude 750
meters.

=Proechimys iheringi panema= subspecies nova

_Type locality._--Campinho, _Colatina_, Espirito Santo, Brazil;
altitude 500 meters. _Type_: Museu Nacional, no. 8288, adult
female; collected on 15 July, 1942, by C. Lako.

_Range._--Known only from the type locality.

_Diagnosis._--Aristiforms moderately wide; tail of approximately
same length as head and body; setiforms Cinnamon; incisive foramen
moderately long and narrow; vomerine sheath incomplete; upper
molariform teeth with two counterfolds, but m3 most frequently
with one.

_Pelage._--_Aristiforms on middorsal region_: Gray basally,
gradually blackening toward tip; total length, 21 to 23 mm;
maximum width, 0.8 mm. _Aristiforms on outer thighs_: Gray, some
gradually blackening toward tip and others with distal part
Cinnamon; total length, 17 to 19 mm; maximum width, 0.7 mm.
_Setiforms on middorsal region_: Gray, gradually blackening
toward tip, but interrupted by Cinnamon, subapical zone; total
length, 18 to 20 mm; maximum width, 0.06 mm. _Setiforms on outer
thighs_: Gray, gradually blackening toward middle, and Cinnamon on
all of distal parts or with tip blackish; total length, 13 to 15
mm; maximum width, 0.09 mm.

_Skull._--Strong, with jugals dorso-ventrally wide; interorbital
region and cranium wide; bullae well inflated; transverse ridge of
jugals not well-developed; postorbital process of zygoma small and
formed only of squamosal; incisive foramen 4.7 × 2.2 mm; vomerine
sheath always incomplete, with maxillary part reduced to small
process; mesopterygoid fossa extending forward as far as middle of
second molars or only slightly short thereof; posterior palatine
foramina at plane of front of first molars.

_Teeth._--All upper molariform teeth with two counterfolds in 4
specimens; one having only one counterfold in M3; 3 with
counterfolds coalesced in one or two molars. Lower molariform
teeth with two counterfolds in one specimen, these counterfolds
not coalesced; m3 with one counterfold in 4 specimens and with two
in one specimen.

_Comparisons._--Differences from _P. denigratus_ and _P. i.
paratus_ are given in the accounts of those animals.

_Specimens examined._--Total number, 5 (MN), from Brazil, Espirito
Santo, _Colatina_, Campinho; altitude 500 meters.

=Proechimys iheringi denigratus= subspecies nova

_Type locality._--Mata do Ribeirão da Fortuna, 40 kilometers west
of Ilheus, _Itabuna_, Bahia, Brazil. _Type_: Museu Nacional, no.
8500, adult male; collected 16 March, 1945.

_Range._--Known only from the type locality.

_Diagnosis._--Aristiforms wide and stiff; tail longer than head
and body; setiforms near (15''_a_) Cinnamon; incisive foramen long
and narrow; vomerine sheath complete; premolars with two
counterfolds, upper molars with one or two, and lower molars with
only one.

_Pelage._--_Aristiforms on middorsal region_: Gray basally,
gradually blackening toward tip; total length, 20 to 22 mm;
maximum width, 1.1 mm. _Aristiforms on outer thighs_: Gray
basally, gradually blackening toward tip or with distal part near
(15''_a_) Cinnamon; total length, 14 to 16 mm; maximum width, 0.5
mm. _Setiforms on middorsal region_: Gray basally, gradually
blackening toward tip but interrupted by near (15''_a_) Cinnamon,
subapical zone 4 mm wide; total length, 18 to 20 mm; maximum
width, 0.05 mm. _Setiforms on outer thighs_: Gray basally,
gradually blackening toward tip but interrupted by wide, near
(15''_a_) Cinnamon, subapical zone.

_Skull._--Slender; nasals short; bullae large and well-inflated;
jugals with conspicuous transverse ridge; postorbital process of
zygoma conspicuous, spiniform and formed almost exclusively by
jugal; incisive foramen elongated and narrow (5 × 1.8 mm);
vomerine sheath complete and formed almost exclusively by
premaxillae; maxillary part of this sheath short and in most
specimens the two parts of sheath completed by vomer itself;
mesopterygoid fossa extending forward as far as middle of second
molars and in some skulls as far as anterior border of second
molars; posterior palatine foramina at anterior plane of first
molars.

_Teeth._--Upper molariform teeth: P4 always with two counterfolds;
M1 with two counterfolds in 65 per cent of specimens but anterior
counterfold poorly developed; rest of specimens with only one
counterfold in M1; M2 with two counterfolds in 50 per cent of
specimens and only one in remainder; M3 with two counterfolds in
only 17 per cent of specimens, and remainder with only one. Lower
molariform teeth: p4 always with two counterfolds; molars always
with only one counterfold.

_Comparisons._--From _P. i. panema_, _denigratus_ differs in: Each
lower molar with only one, instead of with more than one,
counterfold; incisive foramen longer and narrower; vomerine sheath
complete instead of incomplete; aristiforms conspicuously wider;
tail longer.

_Remarks._--One female (SEPFA no. M 17060) captured on 9 January, 1944, gave birth to two females on 26 January, 1944. Each of these young measured 177 mm in total length and weighed 27.8 g. On 4 March, 1944, their measurements were: head and body, 120,120; tail, 120,130; hind foot, 32,33; ear, 21,22; skull:--total length, 36.0,35.0; condyloincisive length, 29.0,29.1; zygomatic breadth, 19.1,18.5; length of nasals, 12.5,11.6; interorbital constriction, 9.3,8.8; cranial breadth, 16.4,16.9; palatilar length, 11.5,10.5; crown length of P4 and M1, 4.3,4.3 mm.

The forest where the animals were captured has a high percentage of deciduous trees in spite of the heavy rainfall in this region. All of the animals were trapped near water. Young were captured from January to May. Most animals have a conspicuous Cinnamon patch on the nuchal region.

_Specimens examined._--Total number, 34 (SEPFA 33, MN 1), from
Brazil, Bahia, _Itabuna_, Mata do Ribeirão da Fortuna.

=Proechimys iheringi paratus= subspecies nova

_Type locality._--Floresta da Capela de São Braz, _Santa Teresa_,
Espirito Santo, Brazil; altitude 630 meters. _Type_: Museu
Nacional, no. 4012, adult female; collected on 24 September, 1940,
by Dr. H. W. Laemmert; SEPFA no. M 8447.

_Range._--Known only from the type locality.

_Diagnosis._--Aristiforms wide and stiff; tail 96 per cent of head
and body; color on setiform Cinnamon-Buff; incisive foramen short
and moderately wide; vomerine sheath complete; all molariform
teeth with two counterfolds.

_Pelage._--_Aristiforms on middorsal region_: Gray basally,
gradually blackening toward tip; total length, 24 to 26 mm;
maximum width, 1.3 mm. _Aristiforms on outer thighs_: Gray
basally, gradually blackening toward middle, and distal parts near
(15''_c_) Pinkish Cinnamon; total length, 18 to 20 mm; maximum
width 0.8 mm. _Setiforms on middorsal region_: Gray basally,
gradually blackening toward tip but interrupted by Cinnamon-Buff,
subapical zone; total length 14 to 16 mm; maximum width, 0.06 mm.

_Skull._--Slender; bullae large and well-inflated; jugals with
conspicuous, transverse ridge; postorbital process of zygoma
moderately developed and involving only squamosal; incisive
foramen short and narrow (4.1 × 2.1 mm); vomerine sheath complete,
with maxillary part short and thick; mesopterygoid fossa extending
forward as far as posterior parts of second molars; posterior
palatine foramina at plane of premolars.

_Teeth._--Upper and lower molariform teeth with two counterfolds.
Counterfolds coalesced in P4 and M1 of one specimen.

_Comparisons._--From _P. i. gratiosus_ and _P. i. panema_,
_paratus_ differs in: all molariform teeth with two, instead of
some with fewer, counterfolds; vomerine sheath complete and thick
instead of usually incomplete; incisive foramen shorter and
narrower; aristiforms conspicuously wider; setiforms Cinnamon-Buff
instead of Ochraceous-Buff and Cinnamon, respectively. Tail 96 per
cent of head and body in _paratus_ instead of 100 per cent as in
_panema_.

_Remarks._--The animals were captured in climax forest.

_Specimens examined._--Total number, 3 (MN), from Brazil, Espirito
Santo, _Santa Teresa_, Floresta da Capela de São Braz; altitude 630
meters.

Proechimys setosus (Desmarest)

_General characters._--Size medium; tail approximately same length
as head and body; aristiforms moderately wide; feet rather large;
ears of medium size; color on upper parts and sides sepia gradually
changing to Ochraceous-Tawny; few differentiated, light-colored
aristiforms present on outer thighs and rump; under surface of body
and inner sides of legs white; tail with white tip and conspicuous,
white pencil; feet white dorsally; skull short and smooth, somewhat
flattened in interorbital region; jugals narrow dorso-ventrally;
incisive foramen moderately long and notably narrow; vomerine
sheath complete and slender; postorbital process of zygoma
spinelike and involving mostly jugal; premolars usually with two
counterfolds; molars with only one counterfold, rarely two in M1 or
in M3.

_Remarks._--The specimens available are undoubtedly faded and, therefore, the colors mentioned above for the upper parts and sides may not correspond to the colors of unfaded pelages. Desmarest (1817:59) describes the color of setosus as similar to that of the "Echimys de Cayenne" (_Proechimys guyannensis_) but being more "rousse." Is. Geoffroy Saint-Hilaire (1840:52) describes the same animal as being "d'un brun roussâtre" on the upper parts.

The _Proechimys_ from Lagoa Santa, Minas Gerais, _"Echimys" elegans_ Lund, is certainly related to _P. iheringi_ as well as to _P. albispinus_. From _P. iheringi_, _elegans_ differs in having a smaller skull with shorter rostrum, narrower incisive foramen, and orthodont incisors. On the other hand the restricted distribution of the aristiforms in the pelage and the white, penicillate tail are points of resemblance to _iheringi_. From _P. albispinus_, _elegans_ differs in having a less spinous pelage and longer tail with white pencil instead of a brown pencil. The skulls, however, are similar, except for the fact that _elegans_ does not have proodont incisors as _albispinus_ sometimes does. Thomas (1921:141) states, after describing the skull of the type of _setosus_, that "Specimens corresponding to this animal have been obtained at Lagoa Santa, Minas, by Lund and others, and at Bahia." Thomas, however, would not have referred to specimens from "Bahia" as being comparable to _elegans_ had they not been different from _albispinus_ which he discussed in the same paper. Also, he would not have confused "specimens comparable to _elegans_" with a subspecies of _P. iheringi_ (_P. i. denigratus_, from southern Bahia) which has opisthodont instead of orthodont incisors. Since French collectors sent material to Europe at the beginning of the 19th century from (southern?) Bahia, possibly _setosus_ came from there.

In the collection of the American Museum of Natural History there is one specimen (AMNH no. 16140) of _Proechimys_, included in the so-called Maximilian Collection. The characters of this specimen agree closely with those of the specimens from Lagoa Santa. The locality of capture of specimen no. 16140 is unknown, but it is reasonable to assume that Prince Maximilian zu Wied obtained it somewhere along his route of travel through southeastern Bahia. Wied (1826:445) mentions "_L[oncheres]. myosuros_ Licht." as "am Parahyba, am Peruhype und Belmonte," which greatly increases the possibility of its having come from southern Bahia. The close similarity to _elegans_ of Wied's specimen indicates that the locality of capture possibly was in the region of the less humid, low escarpments of southern Bahia.

My conclusion is that Wied's specimen corresponds closely to _setosus_ and, tentatively, I identify it as such. "_Echimys elegans_," due to the relationships mentioned above is here considered to be a subspecies of _setosus_.

Among the species described in earlier times, and whose identity was never ascertained, _"Echinomys" fuliginosus_ Wagner seems to be synonymous with _setosus_. Wagner describes the animal as having a tail "apicis versus pilis albidis vestita" and the figure of the cheekteeth (1844, pl. 239 D) shows a typical trilaminate condition which occurs commonly in _elegans_. Moreover, the tail of _fuliginosus_ is only 9 per cent shorter than the head and body and the aristiforms of this subspecies are moderately wide.

=Proechimys setosus setosus= (Desmarest)

_Echimys setosus_ Desmarest (Geoffroy's MS), 1817, Nouv. Dict.
Hist. Nat. nouv. ed., 10:59 (orig. descr.); Is. Geoffroy
Saint-Hilaire, 1838, Comptes Rendus Acad. Sci., Paris, 6(26):886;
Is. Geoffroy Saint-Hilaire, 1840, Mag. Zool., Paris, (ser. 2, année
2):12, 33, 52; Allen, 1899, Bull. Amer. Mus. Nat. Hist.,
12(20):257, 261.

_Echimys cayennensis_ Pictet, 1841, Mém. Soc. phys. Hist. Nat.,
Genève, 9:145; Waterhouse, 1848, Nat. Hist. Mammalia, 2:334.

_Echinomys fuliginosus_ Wagner, 1843, Schreber's Säugethiere,
suppl. 3:343; Wagner, 1844, Schreber's Säugethiere, suppl. 4, pl.
39 D.

_Proechimys setosus_ Allen, 1899, Bull. Amer. Mus. Nat. Hist.,
12(20):264; Thomas, 1921, Ann. Mag. Nat. Hist., 8 (ser. 9):141;
Tate, 1935, Bull. Amer. Mus. Nat. Hist., 68(5):401; Ellerman,
1940, The families and genera of living rodents, Brit. Mus.
(Nat. Hist.), 1:122.

_Proechimys fuliginosus_ Tate, 1935, Bull. Amer. Mus. Nat. Hist.,
68(5): 400; Ellerman, 1940, The families and genera of living
rodents, Brit. Mus. (Nat. Hist.), 1:119.

_Type locality._--Unknown; see remarks under _P. setosus_. _Type_:
Museum d'Histoire Naturelle, Paris, no. A. 7787 (Thomas, 1921:141),
"very imperfect."

_Diagnosis._--Aristiforms wide; P4 and M1 with two counterfolds;
p4 with two counterfolds, one anterior to main fold.

_Pelage._--_Aristiforms on middorsal region_: Gray basally,
gradually blackening toward tip; total length, 18 to 20 mm;
maximum width, 0.8 mm. _Aristiforms on outer thighs_: Color much
faded; total length, 15 to 17 mm; maximum width, 0.3 mm.
_Setiforms on middorsal region_: Color faded; total length, 16 to
18 mm; maximum width, 0.04 mm. _Setiforms on outer thighs_: Color
faded; total length, 10 to 13 mm; maximum width, 0.03 mm.

_Skull._--Short; rostrum short and stout; length of nasals
approximately 15 mm (broken); bullae roundish, smooth and
well-inflated; jugals dorso-ventrally narrow (3.1 mm) with strong
transverse ridge; postorbital process of zygoma spiniform, slender
and involving mostly jugal; incisive foramen narrow (3.8 x 1.7 mm)
and narrowest in posterior part; vomerine sheath complete;
posterior palatine foramina obsolete; mesopterygoid fossa extending
forward as far as middle of second molars.

_Teeth._--Incisors orthodont. P4 with two counterfolds; M1 with
two counterfolds but anterior one notably small; M2 and M3 with
only one counterfold each. In lower jaw: p4 with two counterfolds,
one anterior to main fold; molars with only one counterfold.

_Comparisons._--From _P. s. elegans_, _setosus_ differs in: M1 with
two counterfolds as opposed to only one; M3 with one counterfold
instead of sometimes with two counterfolds; p4 with one counterfold
anterior to main fold and another posterior, instead of both
counterfolds posterior.

_Remarks._--The measurements above were taken from the Maximilian specimen mentioned above. Measurements of the type were given by Desmarest as: head and body, 5-1/2 inches, tail about 6-1/2 inches. Is. Geoffroy Saint-Hilaire (1838:886) corrects these measurements to: head and body 195 mm; tail (part missing), 170 mm.

=Proechimys setosus elegans= (Lund)

_E[chimys]. elegans_ Lund, 1841, Kong. Danske Videnskab. Selsk.
natur-vidensk. math. Afhandl., Kjöbenhavn, 8:99 (orig. descr.).

_Loncheres elegans_ Lund, 1841, Kong. Danske Videnskab. Selsk,
natur-vidensk. math. Afhandl., Kjöbenhavn, 8:245, 266, 294;
Wagner, 1843, Wiegman's Archiv f. Naturg., Berlin, 2 (Jahrg.
9):47.

_Echimys cayennensis_ Waterhouse, 1848, Nat. Hist., Mammalia,
2:337.

_Echinomys cajennensis_ Winge, 1888, Jordfundne og nulevende
Gnavere (Rodentia), E Museo Lundii, Kjöbenhavn, 1(3):71,
pl. 6, figs. 5-6, pl. 7, fig. 1.

_Proechimys setosus_ Thomas, 1921, Ann. Mag. Nat. Hist., 8 (ser.
9):141.

_Proechimys elegans_ Tate, 1935, Bull. Amer. Mus. Nat. Hist.,
68(5):400; Ellerman, 1940, The families and genera of living
rodents, Brit. Mus. (Nat. Hist.), 1:119.

_Type locality._--Lagoa Santa, _Nova Lima_, Minas Gerais, Brazil.
_Type_: Syntypes in Universitets Zoologiske Museum, Kjöbenhavn;
collected by P. W. Lund.

_Range._--Known only from the type locality.

_Diagnosis._--Aristiforms wide; P4 usually with two counterfolds;
M3 sometimes with two counterfolds; p4 with two counterfolds
anterior to main fold.

_Pelage._--_Aristiforms on middorsal region_: Gray basally,
gradually blackening toward tip; total length, 18 to 20 mm;
maximum width, 0.7 mm. _Aristiforms on outer thighs_: Gray
basally, gradually blackening toward tip which is Cinnamon; total
length, 15 to 17 mm; maximum width, 0.3 mm. _Setiforms on
middorsal region_: Whitish basally, gradually blackening toward
tip, but interrupted by Cinnamon, subapical zone; total length, 17
to 19 mm; maximum width, 0.04 mm. _Setiforms on outer thighs_:
Whitish basally, gradually blackening toward tip but interrupted
by near (15''_a_) Cinnamon, subapical zone; total length, 10 to 12
mm; maximum width, 0.03 mm.

_Skull._--Short; rostrum short but not stout; length of nasals 17
mm; bullae large, smooth, and well-inflated; jugals with
conspicuous, transverse ridge; postorbital process of zygoma long,
spiniform and constructed entirely of jugal; incisive foramen
narrow (4 × 1.7 mm); vomerine sheath complete and slender;
posterior palatine foramina obsolete; mesopterygoid fossa
extending anteriorly as far as middle parts of second molars.

_Teeth._--Incisors orthodont. P4 usually with two counterfolds,
rarely with three; upper molars with only one counterfold, but M3
sometimes with two, posterior one being vestigial. Lower
molariform teeth: p4 with two counterfolds, both being anterior to
main fold; molars with only one counterfold.

_Comparisons._--Differences from _P. s. setosus_ are given in the
account of that subspecies.

_Remarks._--According to Lund, these animals are found in the vicinity of small pools, swim well in spite of not having webbed toes, at night go after food and climb the corn stalks, and have their nests in the grass at the margins of the pools.

_Specimens examined._--Total number, 2 (UZM), from Brazil, Minas
Gerais, _Nova Lima_, Lagoa Santa.

=Proechimys albispinus= (Is. Geoffroy)