Chapter VIII: Introduction (7)

From _haidarum_, _alascensis_ differs in that the rostrum and entire preorbital part of the skull is actually as well as relatively much smaller in both sexes. In males of _alascensis_ the length of the skull, and other cranial measurements of length, is more. In males, the mastoid breadth and zygomatic breadth are about the same as in _haidarum_, as also is the weight. M1 is larger but m1 and P4 are smaller. In females the anteroposterior extent of the inner moiety of M1 and length of tympanic bulla are about the same in the two subspecies but all other cranial and dental measurements in _alascensis_ are less. It is 29 per cent lighter. The difference in the preorbital region is of about the same degree as in the males.

Comparisons of the skull with those of _arctica_, _salva_, _initis_, _celenda_, and _seclusa_ are made in the accounts of those subspecies.

_Remarks._--The relatively few specimens known of this race seem always to have been referred to in the literature by the name _alascensis_ and the nomenclatural history is therefore simple. The original materials were obtained by the collector Clark P. Streator and the additional series of skeletons, one with skin, from Windham were procured by Stanton Price, a resident there.

The subspecies is well differentiated from both _arctica_ and _richardsonii_. Although actual intergrades are lacking between _alascensis_ and the two races just mentioned I have no doubt that intergradation occurs with _richardsonii_ and think it probably does also with _arctica_.

The assignment of the three females from Mitkof Island, Zarembo Island, and Loring on Revillagigedo Island, is tentative because each is so young as not to show diagnostic cranial characters. The two other specimens from Revillagigedo Island (Carroll Inlet), labeled as males, are in white winter pelage. Only one, no. 136358, a subadult, is accompanied by a skull. The small size of each specimen, and its cranial characters which are intermediate between those of males and females of _alascensis_ of the adjacent mainland, indicate the existence of a distinct race of weasel on Revillagigedo Island. On the chance that the one specimen with a skull is a dwarf, or is wrongly sexed as seems improbable, the population is tentatively referred to _alascensis_.

_Specimens examined._--Total number, 24, arranged by localities
from north to south. Unless otherwise indicated, specimens are in
the Museum of Vertebrate Zoölogy, University of California.

=Alaska.= Juneau, 5[91]; Taku River, 1; Windham, 9; Mitkof Island,
1; St. John Harbor, Zarembo Island, 1; Wrangel, 1[91]; Helm Bay,
Cleveland Peninsula, 1; Cleveland Peninsula, 2[91]; Revillagigedo
Island, Carroll Inlet, 2[91]; Loring, 1[91].

=Mustela erminea salva= Hall

Ermine

Plates 2, 3, 4, 9, 10 and 11

_Mustela erminea salva_ Hall, Proc. Biol. Soc. Washington, 57:35,
June 28, 1944; Hall, Journ. Mamm., 26:180, July 19, 1945.

_Type._--Male, adult, skull only; no. 74641, Mus. Vert. Zoöl.;
Mole Harbor, Admiralty Island, Alaska, December 27, 1936; obtained
by A. Hasselborg.

The skull (plates 2-4) shows malformation of the frontal sinuses
owing to parasites and lacks osseous tissue where the parasitic
infestation was localized. The skull is unbroken. The teeth all
are present and entire.

_Range._--Admiralty Island, Alaska. See figures 25, 26 on pages
95, 134.

_Characters for ready recognition_ (known only from
skulls).--Differs from males of _M. e. alascensis_ in overall
depth of braincase which is more than 89 per cent of orbitonasal
length; from _M. e. initis_, in males, in that orbitonasal length
and mastoid breadth total less than 35 mm., weight of skull and
lower jaws less than 2.1 grams; from _M. e. celenda_, in males, in
that breadth of rostrum measured across lacrimal processes less
than a third of basilar length.

_Description._--_Size._--Male: An adult from Gambier Bay measures:
Total length, 320; length of tail, 95; length of hind foot, 45 (41
in dry skin).

Female: A subadult from Hawk Inlet, measures: Total length, 250;
length of tail, 70; length of hind foot, 33.

_Color._--As described in _Mustela erminea richardsonii_ except
that least width of color of underparts in four individuals 40
(38-43) per cent of greatest width of color of upper parts. Black
tip of tail, in two individuals for which external measurements
are given, amounting to 50 and 40 mm. respectively which is 53 and
57 per cent of length of tail-vertebrae.

_Skull._--Male (type and 4 adult topotypes): See measurements and
plates 2-4. As described in _Mustela erminea richardsonii_ except
that: Weight, 1.7 (1.5-1.9) grams; basilar length, 37.8
(36.4-39.5, extremes are in subadults); length of tooth-rows more
or less (usually more) than length of tympanic bulla; interorbital
breadth rarely more than distance between glenoid fossa and
posterior border of external auditory meatus.

Female (2 ad. and 1 ad.-sad. topotypes): See measurements, and
plates 9-11. As described in _Mustela erminea richardsonii_ except
that: Weight, 0.9 (0.8-1.0) grams; basilar length, 33.0
(32.0-33.6); length of tooth rows approximately same as length of
tympanic bulla; breadth of rostrum approximately 30 per cent of
basilar length.

From _alascensis_, _salva_ differs in that males have the preorbital region slightly wider in relation to the length of the tympanic bulla; also the braincase is smaller, actually as well as in comparison with the preorbital part of the skull. The tympanic bullae do not project so far below the squamosals and the braincase itself is shallower, in adults averaging only 11.5 mm. as against 12.5 mm. The overall depth of the braincase, including the tympanic bullae, when divided into the orbitonasal length gives an average of 93 (90-97) per cent whereas in _alascensis_ the figure is only 85 (78-88) per cent. On this basis alone, everyone of the adult skulls of the two races can be distinguished. The females and subadult males show the same tendency to reduction in depth of braincase but not every individual among them can be surely distinguished. By weight the skull of _salva_ of corresponding sex is only about 6 per cent smaller. Comparisons with _initis_ and _celenda_ are made in the accounts of those subspecies.

_Remarks._--Most of the specimens seen were collected by Allen E. Hasselborg, resident on Admiralty Island. On the basis of skulls--few skins, and measurements taken in the flesh, are available--_salva_ more closely resembles _alascensis_ than does any other subspecies so far known from southeastern Alaska. The race on Admiralty Island is only slightly differentiated from _alascensis_ of the adjacent mainland.

_Specimens examined._--Total number, 26, all from Admiralty
Island, Alaska, arranged in general by localities from north to
south, and unless otherwise indicated in the Museum of Vertebrate
Zoölogy, University of California.

=Alaska.= Admiralty Island: Hawk Inlet, 2; Seymour Canal, 4; Mole
Harbor, 18 (skulls only); Gambier Bay, 1; no locality more
definite than Admiralty Island, 4 (1 in U. S. Nat. Mus.).

=Mustela erminea initis= Hall

Ermine

Plates 4, 5 and 6

_Mustela erminea initis_ Hall, Proc. Biol. Soc. Washington, 57:37,
June 28, 1944; Hall, Journ. Mamm., 26:180, July 19, 1945.

_Type._--Male, adult, skull and skin; no. 289, Mus. Vert. Zoöl.;
Saook Bay, Baranof Island, Alaska; October 9, 1907; obtained by A.
Hasselborg, original no. 4.

The top of the skull is fractured on the left side from the
anterior nares posteriorly through the postorbital process to the
posterior root of the zygomatic arch. On the left lower jaw the
canine and three incisors are missing; otherwise the teeth all are
present and entire.

The skin is in process of molt, approximately nine-tenths of the
incoming white pelage being in place. The skin is well made and in
a good state of preservation.

_Range._--Chichagof and Baranof islands, Alaska. See figures 25,
26 on pages 95, 134.

_Characters for ready recognition_ (only males known).--Differs
from _M. e. arctica_, in that proximal two-thirds of under side of
tail colored same as upper parts rather than same as underparts,
zygomatic breadth less than distance between last upper molar and
jugular foramen; from _M. e. salva_ in that orbitonasal length and
mastoid breadth total more than 35 mm., weight of skull and lower
jaws more than 2.1 grams; from _M. e. alascensis_, by total length
more than 317, black tip of tail more than 57 per cent of length
of tail-vertebrae, interorbital breadth more than 10.3 and equal
to, instead of less than, distance between glenoid fossa and
posterior border of external auditory meatus; from _M. e. celenda_
by chest white (not mostly covered by brown patch), breadth of
rostrum measured across lacrimal processes less than a third of
basilar length; from _M. e. seclusa_ in zygomatic breadth more
than distance between last upper molar and jugular foramen.

_Description._--_Size._--Male: The type and an adult topotype
measure, respectively, as follows: Total length, 330, 320; length
of tail, 95, 95; length of hind foot, 45, 45.

Female: No external measurements available.

_Color._--As described in _Mustela erminea richardsonii_ except
that least width of color of underparts averages, in two young
female topotypes, 50 (49, 50) per cent of greatest width of color
of upper parts. Black tip of tail in three young female topotypes
averaging 54 (52-55) mm. which is 67 (63-69) per cent of length of
tail-vertebrae.

_Skull._--Male (illustrated by type and 1 ad. topotype): See
measurements and plates 4-6. As described in _Mustela erminea
richardsonii_ except that: Weight, 2.3 and 2.5 grams; basilar
length, 39.6, and 40.5; interorbital breadth equal to distance
between glenoid fossa and posterior border of external auditory
meatus.

Female: No adults available.

From _salva_, _initis_ differs in that skulls of males average larger in every measurement taken, being 41 per cent heavier. Relative to the basilar length, the interorbital and preorbital parts of the skull are larger; the relatively greater interorbital and mastoid breadths are particularly noticeable. Although the depth of the braincase, including the tympanic bullae, is both relatively as well as actually more than in _salva_, the depth is relatively less than in _alascensis_ which otherwise differs from initis in about the same way that _salva_ differs from _initis_. Whereas the interorbital breadth in _initis_ is about equal to the distance between the glenoid fossa and the posterior border of the external auditory meatus, the interorbital breadth is uniformly less than this distance in both _salva_ and _alascensis_. In comparison with _seclusa_ the teeth are of the same size but all measurements of the skull are larger. The skull of _initis_ is 25 per cent heavier. In relation to the basilar length, the interorbital and preorbital parts of the skull are much less in _initis_. The preorbital and interorbital regions in _initis_ are relatively smaller in comparison also with _arctica_. The one measurement of interorbital breadth in _initis_ is greater in relation to the basilar length than in _kadiacensis_ but the rostral region, and all that part of the skull anterior to the braincase, is relatively smaller in _initis_.

_Remarks._--The two adult males, nos. 286 and 289 from Saook Bay, provide convincing evidence of the existence of a distinct race of weasel on Baranof Island. Three other young specimens, almost subadult, from the same place are labeled as males although the basilar lengths of these skulls are only 35.5, 35.9 and 37.3 millimeters as against 39.6 and 40.5 in the two adult males. The difference in size is too great to be age-variation. The fact that 3 are definitely of one category and 2 of the other makes it doubtful that individual variation accounts for the differences. The small size of these 3 specimens and the fact that in each the anterior margin of the tympanic bulla is flush with the squamosal rather than protruded from the braincase, suggests that the three are females. If they are females, the amount of secondary sexual variation is rather less than would be expected by analogy with the amount obtaining in _alascensis_ on the mainland and in _salva_ on Admiralty Island. Another possibility that I can not disprove is that two stocks of weasels persist on Baranof Island, the two larger specimens being descendants of the stock which first became established on the island and the three smaller specimens being descendants of an individual ermine, or of ermines, that were rafted or otherwise transported to the island at a considerably later date. Assuming for the moment that there are two stocks, it must be admitted that each one differs from any stock known from elsewhere. Therefore, each stock would be presumed to have been long resident on the island. But--two stocks as closely related as the two in question would not be expected to persist for long in an area as small as that of Baranof Island because competition would give one the ascendancy. Therefore, the first suggestion, namely that the three smaller animals are really females, seems the more probable. The feasible way to clear up the present uncertainty is, of course, to obtain additional specimens, carefully labeled as to sex. Yet another reason why additional collecting is desirable in this area is to ascertain whether there is subspecific differentiation between the ermines of Baranof and Chichagof islands. The one specimen available from the latter island, although in general like the three smaller animals from Baranof Island, differs in the fuller (less scooped out) medial side of the tympanic bulla and to a slight degree in each of some other features. This specimen from Chichagof Island is labeled as a male also.

_Specimens examined._--Total number, 6, arranged by localities
from north to south, and in the Museum of Vertebrate Zoölogy,
University of California.

=Alaska.= Chichagof Island, Freshwater Bay, 1. Baranof Island,
Saook Bay, 5.

=Mustela erminea celenda= Hall

Ermine

Plates 5, 6 and 7

_Mustela erminea celenda_ Hall, Proc. Biol. Soc. Washington, 57:38,
June 28, 1944; Hall, Journ. Mamm., 26:181, July 19, 1945.

_Type._--Male, adult, skull and skin; no. 130987, U. S. Nat. Mus.,
Biol. Surv. Coll.; Kasaan Bay, Prince of Wales Island, Alaska;
June 16, 1903; obtained by Cyrus Catt; original no. 4407X.

The skull has a piece 1.5 mm. long broken out of the left
zygomatic arch. P2 is absent on both sides. The right I1, and the
left I1 and I2 are missing. The skin, in summer pelage, is fairly
well made. A scrotal pouch attests to the correctness of the sex
recorded on the label. The rostral part of the skull is smaller
than in average-sized males of corresponding age.

_Range._--Prince of Wales, Dall, and Long islands, Alaska. See
figures 25, 26 on pages 95, 134.

_Characters for ready recognition_ (only males known).--Differs
from _M. e. alascensis_ and _initis_ in chest mostly covered by
brown patch, not white, and breadth of rostrum measured across
lacrimal processes more than a third of basilar length, which
cranial character serves to distinguish also _salva_; from _M. e.
seclusa_ in zygomatic breadth less than distance between last
upper molar and jugular foramen; from _M. e. haidarum_ in chest
white (not mostly covered by brown patch), proximal two-thirds of
underside of tail colored like upper parts rather than underparts,
basilar length more than 38.2 mm.

_Description._--_Size._--Male: Seven adults and subadults from
Prince of Wales Island, yield average and extreme measurements as
follows: Total length, 286 (277-304); length of tail, 77 (74-85);
length of hind foot, 36 (35.5-40.5).

Female: No specimen available.

_Color._--As described in _Mustela erminea richardsonii_ except
that upper parts about tone 3 of dark Chocolate Brown of Oberthür
and Dauthenay, pl. 342; lower throat and chest covered by a large
patch of same color as upper parts; color of underparts extending
to toes but in interrupted fashion on both fore-and hind-feet;
least width of color of underparts averaging, in four males from
Prince of Wales Island, 41 (38-49) per cent of greatest width of
color of upper parts. Black tip of tail averaging, in 8 males in
winter pelage, 65 (59-78) mm. which is 84 (69-92) per cent of
length of tail-vertebrae.

From its geographic neighbors _alascensis_ and _initis_, _celenda_
differs in darker color of upper parts, presence rather than
absence of patch of dark color on lower throat and chest, and
longer black tip on tail. From _haidarum_, _celenda_ differs in
darker color of upper parts, presence rather than absence of
patch of dark color on lower throat and chest, narrower
light-colored under parts, black tip of tail averaging less rather
than more than nine-tenths of length of tail-vertebrae and ventral
face of tail colored like upper parts rather than like underparts.

_Skull._--Male (illustrated by 5 adults): See measurements and
plates 5-7. As described in _Mustela erminea richardsonii_ except
that: Weight, 2.3 (2.2-2.5) grams; basilar length, 39.5
(38.9-40.7) mm.; length of tooth-rows more than length of tympanic
bulla; breadth of rostrum measured across lacrimal processes more
than a third of basilar length; interorbital breadth more than
distance between glenoid fossa and posterior border of external
auditory meatus; zygomatic breadth more or less than (about equal
to) distance between last upper molar and jugular foramen.

Female.--Complete skull of adult unavailable.

Differences from _richardsonii_ are indicated in the formal description just given. Additional to differences therein noted, _celenda_ differs from _initis_ in larger interorbital and preorbital parts of the skull although dimensions of other parts of the skull and the teeth are about the same or even less. From _salva_, _celenda_ differs in larger average size in every measurement taken, except for the inner moiety of M1 which is about the same. The skull of _celenda_ is 35 per cent heavier. In relation to the basilar length the skull of _celenda_ is wider, especially in the interorbital and preorbital regions. In comparison with _alascensis_ the tympanic bullae are of approximately the same length; otherwise essentially the same differences obtain as are noted in comparison with _salva_ and the zygomatic breadth is relatively more in _celenda_. From _seclusa_, in which the teeth are of comparable size, _celenda_ differs in that every cranial measurement is more and the skull is 28 per cent heavier. Because the skull of _celenda_ is so much longer, its dimensions in other planes are less in relation to the length than in _seclusa_. _M. e. celenda_ is larger in every part measured than _haidarum_, 21 per cent heavier, and in relation to the basilar length the interorbital, and preorbital, parts of the skull are smaller, the braincase is shallower, and the skull is relatively wider across the zygomata and mastoid processes. In comparison with _kadiacensis_, differences are: 26 per cent lighter, skull shorter; in relation to the basilar length, braincase shallower as measured at the anterior end of the basioccipital, tooth-rows shorter but orbitonasal length more. In comparison with _arctica_ all parts measured of the teeth and skull of _celenda_ are smaller and its skull is 34 per cent lighter. In relation to the basilar length, the interorbital breadth of _celenda_ is only slightly less but its skull is narrower across the rostrum and zygomata, the tooth-rows are shorter, and the braincase is shallower.

_Remarks._--The late George Willett in the course of his work in Alaska collected most of the known specimens of this strongly differentiated subspecies. In both coloration and cranial characters the distinguishing features are so well marked that the zoölogist could with reason accord full specific rank to _celenda_. Nevertheless it obviously is an ermine. Also, races from other islands of southeastern Alaska tend to bridge the gap, as regards cranial features, between _celenda_ and the mainland ermine. The specimen from Dall Island agrees in all respects with topotypes. The specimen from Howkan on Long Island is in white winter pelage and the skull has suffered shrinkage from some chemical solution; the reference of this specimen to _celenda_ is tentative.

_Specimens examined._--Total number, 25, as follows: Arranged by
localities from north to south. Unless otherwise indicated, in U.
S. National Museum.

=Alaska.= Prince of Wales Island: Craig, 18 (10 in Mus. Vert.
Zoöl., and 8 in Los Angeles Mus. Hist. Art and Sci.); Kasaan Bay,
2; no locality more definite than the Island itself, 3; Dall
Island, Otter Harbor, 1 (Los Angeles Mus. Hist. Art and Sci.).
Long Island, Howkan, 1 (Field Mus. Nat. Hist.).

=Mustela erminea seclusa= Hall

Ermine

Plates 5, 6 and 7

_Mustela erminea seclusa_ Hall, Proc. Biol. Soc. Washington, 57:39,
June 28, 1944; Hall, Journ. Mamm., 26:181, July 19, 1945.

_Type._--Male, adult, skull alone; no. 31232, Mus. Vert. Zoöl.;
Port Santa Cruz, Suemez Island, Alaska; March 24, 1920; obtained
by George Willett.

The skull (plates 5-7) is complete and unbroken. Of the upper
incisors only right I3 is present. Otherwise the teeth are present
and unbroken.

_Range._--Known only from the type locality. See figures 25, 26 on
pages 95, 134.

_Characters for ready recognition_ (only the male known).--Differs
from _M. e. celenda_ in basilar length less than 38.2, from _M. e.
salva_, _initis_ and _haidarum_ in zygomatic breadth more than
distance between last upper molar and jugular foramen.

_Description.--Size_ and _Color._--No external measurements or
skins available.

Skull.--Male: See measurements and plates 5-7. As described in
_Mustela erminea richardsonii_ except that: Weight, 1.8 grams;
basilar length, 34.3; length of tooth-rows about the same as
length of tympanic bulla; breadth of rostrum measured across
lacrimal processes more than a third of basilar length;
interorbital breadth more than distance between glenoid fossa and
posterior margin of external auditory meatus; zygomatic breadth
more than distance between last upper molar and jugular foramen.

Female.--Skull not available.

From _alascensis_ and _salva_, _seclusa_ differs in larger teeth, shorter skull, much larger preorbital and interorbital regions, actually as well as in relation to basilar length. Excepting the teeth, which are of about the same size, the same general differences obtain in comparison with _initis_ which, however, is 29 per cent heavier.

From _celenda_, _seclusa_ differs in smaller skull in all parts measured, being 22 per cent lighter. The teeth are about the same size. In relation to its length the skull of _seclusa_ is much broader and deeper. From _haidarum_, _seclusa_ differs in: teeth larger; skull shorter and more convex in dorsal outline along median longitudinal axis; in relation to basilar length, skull broader, deeper and braincase relatively shorter.

_Remarks._--The characters shown in the one available skull are far outside the limits of individual variation for other known subspecies. Other specimens are much to be desired to ascertain what the "average" individual is like and to learn the characters of the female.

_Specimen examined._--One, the holotype.

=Mustela erminea haidarum= (Preble)

Ermine

Plates 5, 6, 7, 11, 12 and 13

_Putorius haidarum_ Preble, Proc. Biol. Soc. Washington, 12:169,
August 10, 1898.

_Mustela haidarum_, Miller, U. S. Nat. Mus. Bull., 79:97, December
31, 1912.

_Mustela erminea haidarum_, Hall, Proc. Biol. Soc. Washington,
57:38, June 28, 1944; Hall, Journ. Mamm., 26:181, July 19, 1945.

_Type._--Male, adult, skull, skeleton and skin; no. 94430, U. S.
Nat. Mus., Biol. Surv. Coll.; Massett, Queen Charlotte Islands,
British Columbia; March 17, 1898; obtained by J. H. Keen; original
no. 1800x.

The skull is unbroken and complete except for osseous tissue
destroyed in the region of each postorbital process; this is the
result of infestation of the frontal sinuses by parasites. The
skeleton is complete down to the distal ends of the tibiae; the
more distal bones are in the skin. The first, right, upper incisor
is missing. Otherwise the teeth all are present and entire.

The skin is in the white, winter pelage but the new under fur is
visible along the back and on the head although mostly covered
with white hair.

_Range._--Queen Charlotte Islands. See figure 25, page 95.

_Characters for ready recognition._--Differs from _M. e. celenda_
in chest white (not mostly covered by brown patch), proximal
two-thirds of under side of tail colored like underparts instead
of upper parts, in males basilar length less than 38.2; from _M.
e. seclusa_, in male, in zygomatic breadth less than distance
between last upper molar and jugular foramen; from _M. e.
richardsonii_ and _alascensis_, in both sexes, in proximal
two-thirds of under side of tail colored like underparts instead
of upper parts, interorbital breadth not less than distance from
glenoid fossa to posterior margin of external auditory meatus;
from _M. e. anguinae_ and _fallenda_, in both sexes, in
light-colored underparts more than half the width of dark-colored
upper parts, proximal two-thirds of under surface of tail colored
like underparts instead of upper parts, interorbital breadth equal
to or more than distance between glenoid fossa and posterior
margin of external auditory meatus.

_Description.--Size._--Male: Two adults, U.S.N.M., no. 100622,
from Cumsheva Inlet, and Amer. Mus. N. H., no. 37411, and the
type, measure, respectively, as follows: Total length, 283, 290,
275; length of tail, 70, 75, 60; length of hind foot, 39, 40, 37.

Female: Corresponding measurements of an adult, no. 100624, and a
young individual, no. 100623, each from Cumsheva Inlet, are: 252,
250; 63, 61; 31, 32.

_Color._--As described in _Mustela erminea richardsonii_ except
that underparts not Sulphur Yellow but ranging from near (_e_)
Colonial Buff through Marguerite Yellow to almost pure white;
color of underparts extends distally on posterior sides of
forelegs and onto toes but in many specimens interrupted at wrist
by color of upper parts; color of underparts extends onto proximal
three-fourths of under side of tail as length of tail is measured
along tail-vertebrae; least width of color of underparts
averaging, in 5 males, 79 (66-130) per cent of greatest width of
color of upper parts. Black tip of tail in same males averaging 62
(60-70) mm. which is 92 (83-115) per cent of length of
tail-vertebrae.

The close correspondence in color-pattern of this weasel with the
Arctic races, _arctica_, _polaris_, _semplei_ and _kadiacensis_ is
noteworthy, and distinguishes it from weasels on the adjacent
mainland and adjoining islands to the north and south. The color
of the upper parts is darker than in the four Arctic races named.

_Skull._--Male (7 adults): See measurements and plates 5-7. As
described in _Mustela erminea richardsonii_ except that: Weight,
1.9 (1.7-2.0) grams; basilar length, 36.7 (35.6-37.5); length of
tooth-rows more than length of tympanic bullae; breadth of rostrum
measured across lacrimal processes more than a third of basilar
length; interorbital breadth more than distance between glenoid
fossa and posterior margin of external auditory meatus; zygomatic
breadth barely less than distance between last upper molar and
jugular foramen.

Female (2 adults): See measurements and plates 11-13. As described
in _Mustela erminea richardsonii_ except that: Weight, 1.3 and 1.4
grams; basilar length, 34.2; length of tooth-rows more or less
than (about equal to) length of tympanic bulla; breadth of rostrum
more than 30 per cent of basilar length; interorbital breadth not
less than distance between glenoid fossa and posterior margin of
external auditory meatus.

From _richardsonii_, _haidarum_ differs in that skull of the male is actually larger in its anterior part (breadth of rostrum, interorbital breadth and orbitonasal length) but all measurements of other parts average less. In relation to the basilar length, the tympanic bulla is shorter but all other measurements are more. In the skull of the female, which is 23 per cent heavier, the width of the tympanic bulla and anteroposterior extent of the inner lobe of M1 are the same; in all other measurements the female of _haidarum_ is larger, and in relation to the basilar length all measurements are more except the depth of the skull at the anterior margin of the basioccipital and the width of the tympanic bulla, which are less. By actual weight the skull of the male is 25 per cent lighter and the skull of the female 24 per cent heavier than in _richardsonii_. From _fallenda_ and _anguinae_, _haidarum_ differs in that measurements of the skulls of both sexes either average more, or are uniformly more, with two exceptions. These are the lesser length and breadth of the tympanic bulla, in comparison with males of _fallenda_, and the dimensions of M1 which are about the same in all three races concerned. The pre-and interorbital parts are larger in relation to the remainder of the skull. The postorbital breadth is actually a third more than in _fallenda_. In relation to the basilar length, the tympanic bulla is shorter and the braincase deeper than in males of _anguinae_. The skull of the male is 27 per cent heavier than that of _fallenda_ and 58 per cent heavier than that of _anguinae_. The skull of the female is 59 and 50 per cent heavier than those of _fallenda_ and _anguinae_, respectively. Comparison of the skull with those of _alascensis_, _celenda_ and _seclusa_ has been made in the accounts of those subspecies.

_Remarks._--The available specimens of this ermine were obtained by J. H. Keen in 1898, Wilfred H. Osgood and E. A. Lewis in 1900, W. W. Brown in 1914, J. A. Munro in 1917 and 1918, and Allan Brooks in 1920. _M. e. haidarum_ has more claim to full specific status than any other race of ermine because the diagnostic structural features are numerous and individually of relatively great degree. Indeed, individual variation appears not to bridge the gap between any population of _haidarum_ and other subspecies and strong reasons could be advanced for according _haidarum_ the status of a full species. It differs from the subspecies of _erminea_ on the adjoining mainland and adjoining islands to the north and south and agrees with the Arctic races (_arctica_, _polaris_, _semplei_ and _kadiacensis_) in great extent of the color of the underparts, extension of this color onto the underneath side of the tail, long black tip of the tail and general form of the skull including the relatively heavy preorbital region. The color although darker than in the Arctic subspecies, is lighter than in the insular races immediately to the north and south. In combination, the features mentioned could be taken as indication that _haidarum_ is a relict population from a former glacial period. Assuming that it is a relict population, the color may have become slightly darker since that period but the main response appears to have been a decrease in size for this is a much smaller animal than the Arctic ermines. The size is about what would be expected if one were to judge by the slightly larger ermines on the islands of southeastern Alaska to the north and the smaller ermine on Vancouver Island to the south.

The ermines of the islands of southeastern Alaska, excepting possibly the incompletely known _seclusa_, have fewer characters of the Arctic races and more characters of the races of the adjoining mainland. Therefore, a possible inference is that the distinctive characters of ermines of the Alaskan islands developed with the aid of isolation from stocks which reached the islands after the glacial period. _M. e. haidarum_ may have found its way to the Queen Charlotte Islands in the glacial period.

_Specimens examined._--Total number, 17, as follows. Arranged by
locality from north to south. Unless otherwise indicated,
specimens are in the U. S. National Museum.

=British Columbia.= Queen Charlotte Islands. Masset, 7 (4[74],
1[2], 1[59]); Skidegate, 1; Graham Island, 5 (2[94], 1[77], 1[2]);
Cumsheva Inlet, 3; no locality more definite than Queen Charlotte
Islands, 1[2].

=Mustela erminea anguinae= Hall

Ermine

Plates 5, 6, 7, 11, 12 and 13

_Mustela cicognanii anguinae_ Hall, Univ. California Publ. Zoöl.,
38:417, November 8, 1932.

_Putorius cicognanii_, Baird, Mamm. N. Amer., p. 161, 1858 (part).

_Putorius streatori_, Swarth, Univ. California Publ. Zoöl., 10:102,
February 13, 1912.

_Mustela erminea anguinae_ Hall, Journ. Mamm., 26:79, February 27,
1945; Hall, Journ. Mamm., 26:181, July 19, 1945.

_Type._--Male, adult, complete skeleton (no skin); no. 12482, Mus.
Vert. Zoöl., French Creek, Vancouver Island, British Columbia;
found as a desiccated carcass on May 1, 1910; obtained by Harry S.
Swarth.

_Range._--Vancouver Island, British Columbia. See figures 25, 27
pages 95, 149.

_Characters for ready recognition._--Differs from _M. e.
haidarum_, in both sexes, in light-colored underparts less than
half the width of dark-colored upper parts, proximal two-thirds of
under surface of tail colored like upper parts instead of
underparts, interorbital breadth less than distance between
glenoid fossa and posterior margin of external auditory meatus;
from _M. e. fallenda_, in both sexes, anterior margin of tympanic
bullae flush with squamosal rather than projecting from floor of
braincase, in males by sagittal crest absent, in females by total
length more than 238 and tooth-rows about same length as, instead
of longer than, tympanic bulla; from _M. e. streatori_, in male,
by sagittal crest absent and hind foot ordinarily more than 33.5,
in female by hind foot more than 27.5, basilar length more than
30.2; from _M. e. olympica_, in males, by greater average size,
hind foot ordinarily more than 33.4 and interorbital breadth
ordinarily more than 8.5, in females by larger size, total length
more than 235, tail more than 65, hind foot more than 27.5,
basilar length more than 30.2.

_Description._--_Size._--Male: Sixteen adults and subadults yield
average and extreme measurements as follows: Total length, 272
(261-284) mm.; length of tail, 81 (74-86); length of hind foot,
35.0 (33.5-36).

Female: Five adults and subadults have corresponding measurements
as follows: 247 (241-257); 69 (66-73); 30.0 (28.0-32.0).

_Color._--As described in _Mustela erminea streatori_ except that:
occasionally white in winter; upper parts about tone 2 of Dark
Chocolate of Oberthür and Dauthenay; least width of color of
underparts averaging, in 7 adult males, 6 (0-15) per cent of
greatest width of color of upper parts. Black tip of tail in same
series averaging 37 (26-46) mm. which is 46 (32-54) per cent of
length of tail-vertebrae.

_Skull._--Male (based on 13 adults): See measurements and plates
5-7. As described in _Mustela erminea richardsonii_ except that:
Weight, 1.2 (1.0-1.3) grams; basilar length, 34.0 (32.5-35.6);
length of tooth-rows more or less (usually less) than length of
tympanic bulla.

Female (based on 5 adults): See measurements and plates 11-13. As
described in _Mustela erminea richardsonii_ except that: Weight
0.9 (0.77-1.06) grams; basilar length, 31.5 (30.9-31.8) grams;
length of tooth-rows more or less than (approximately same as)
length of tympanic bulla; breadth of rostrum more than 30 per cent
of basilar length.

The sexual dimorphism in the skull is slight, the skull of the male being only a third heavier than that of the female. In _fallenda_ of the adjacent mainland to the east the male is three-fourths heavier than the female. In comparison with _fallenda_, males are smaller, averaging less in every cranial and dental measurement taken and by weight are a fifth lighter; sagittal crest absent rather than present; tympanic bullae flush with squamosal rather than projecting below floor of braincase; in relation to basilar length, tympanic bullae smaller, braincase deeper and broader, skull wider interorbitally and across zygomata. Females are larger than in _fallenda_, and with one exception average larger in every cranial and dental measurement taken, being 6 per cent heavier. The one exception mentioned is the lesser actual length of the tympanic bulla in _anguinae_, in which the length of the tooth-rows is about the same as, rather than less than, the length of the tympanic bulla. The postorbital breadth is greater than in _fallenda_ and the anterior edges of the tympanic bullae are flush with the squamosals rather than projecting below the floor of braincase. In relation to the skull as a whole the preorbital and interorbital parts are larger.

In comparison with _streatori_, skulls of males are of about the same size, _anguinae_ being only 9 per cent heavier. The length of the tooth-rows is ordinarily less than, rather than about equal to, the length of the tympanic bulla; sagittal crest wanting rather than present since in _anguinae_ the temporal muscles meet usually only at the posterior end of the braincase instead of all along the midline on its top; tympanic bullae narrower and more nearly flush with squamosal (less protruded from braincase). Relative to the basilar length, the zygomatic breadth is more, the tympanic bullae are narrower, and the braincase is deeper at the anterior end of the basioccipital. The female is 41 per cent heavier than _streatori_, there being no overlap in most cranial and dental measurements. M1, however, is approximately the same size in each subspecies. The tooth-rows and tympanic bulla are of almost equal length whereas in _streatori_ the length of the tooth-rows is less than that of the bulla.

Differences from _olympica_, in males, are: M1 shorter; all other measurements of teeth and parts of skull averaging larger; skull 20 per cent heavier; tooth-rows averaging shorter than tympanic bulla rather than about the same; relative to basilar length, braincase deeper at anterior end of basioccipital and tooth-rows shorter. The skull of the female is 64 per cent heavier, larger in every measurement taken without overlap; temporal ridges meeting, rather than separated, at lambdoidal crest; length of tooth-rows about equal to, rather than shorter than, tympanic bulla; in relation to basilar length, skull deeper, orbitonasal length more, mastoid and zygomatic breadths more, and tympanic bullae shorter.

_Remarks._--References in the literature to this insular race mostly were under the name _streatori_ until 1932 when in the course of the present study the name _anguinae_ was proposed. A few specimens have been taken by nearly every student of small mammals who has collected on Vancouver Island. Arthur Peake and Herbert Laing have probably collected more specimens than any other two zoölogists.

_M. c. anguinae_ is noteworthy for the slight secondary sexual variation in size; the disparity between the two sexes is less than in any other American subspecies of _erminea_. By linear measurement the body of the female is only 7 per cent shorter than in the male (178 versus 191 mm.). Linear measurements and weights of the skulls of the two sexes are further indicative of this approximation in size. By weight the skull of the female is only a fourth lighter than that of the male, or, stated in another way, the male's skull is only a third heavier (1.2 versus 0.9 grams).

No geographic variation has been detected between lots of specimens from different parts of Vancouver Island. The one specimen available from Salt Spring Island presents no obvious differences from selected individuals from Vancouver Island.

The winter pelage is more often brown than white. Of 17 specimens seen in winter pelage or in transition pelage, only 6 are white. These 6 are from Comox, Stamp River, Hilliers, Jeune Landing and Port Alice. Of the 34 specimens in brown pelage, 7 have the dark color of the upper parts meeting on the abdomen. Six of the 34 have brown color on the pectoral region. In two, this is a separate patch but in the other four the dark color is a continuation of the upper parts and extends in front of each foreleg over part of the pectoral region, but the two extensions, one from either side, do not meet on the underparts. The color of the lips was recorded in 22 individuals: one had both the upper and lower-lips white; 7 had the upper lips brown and the lower lips white; in 14 both the upper and lower-lips were brown.

_Specimens examined._--Total number, 40, listed by localities from
north to south as follows. Unless otherwise indicated, specimens
are in the National Museum of Canada.

=British Columbia.= Vancouver Island: Cape Scott, 4; Shushartie,
1; Quatsino, 1[74]; Jeune Landing, 1[74]; Port Alice, 5[15];
Marble Creek, Quatsino Sound, 1[22]; Port Hardy, 5; Sayward, 2;
Bear Lake, 4; Bear River, 1; Comox, 4(3[85]); Stamp River,
Alberni, 1[31]; Errington, 1[74]; French Creek, 1[74]; Hilliers,
1[74]; Craigs Crossing, 1[74]; Nanaimo, 2[22]; Cowichan Lake,
1[22]; Duncan, 2[85]; Salt Spring Island, 1[85].

=Mustela erminea fallenda= Hall

Ermine

Plates 5, 6, 7, 11, 12 and 13

_Mustela erminea fallenda_ Hall, Journ. Mamm., 26:79, February 27,
1945; Hall, Journ. Mamm., 26:181, July 19, 1945.

_Putorius streatori_ Merriam, N. Amer. Fauna, 11:13, June 30, 1896
(part-Sumas).

_Type._--Male, adult, skull and skin; no. 7096, Nat. Mus. Canada;
Huntingdon, British Columbia; May 21, 1927; obtained by C. H.
Young, original no. 317.

The brown summer skin is well made. The skull (plates 5-7) is
complete. Right p2 has the crown broken away; otherwise the teeth
all are present and entire.

_Range._--On mainland in immediate vicinity of coast from probably
opposite Texada Island, British Columbia, south to Lake Whatcom,
Washington, and east to Mount Baker Range on International
boundary. See figures 25, 27 on pages 95, 149.

_Characters for ready recognition._--Differs from _M. e.
haidarum_, in both sexes, in light-colored underparts less than
half the width of dark-colored upper parts, proximal two-thirds of
under surface of tail colored like upper parts instead of
underparts, interorbital breadth less than distance between
glenoid fossa and posterior margin of external auditory meatus;
from _M. e. richardsonii_ in both sexes, by upper lips brown
rather than white, in males hind foot less than 41 and basilar
length less than 38.3, in females hind foot less than 29, basilar
length less than 31.4 and breadth of rostrum more, instead of
less, than 30 per cent of basilar length; from _M. e. invicta_, in
both sexes, by upper lips brown (not white); in males by skull
averaging shorter (basilar length 35.7 versus 37.0); in females by
breadth of rostrum more, instead of less, than 30 per cent of
basilar length; from _M. e. anguinae_, in both sexes, by anterior
margin of tympanic bulla projecting from floor of braincase rather
than flush with squamosal (the difference is slight in females),
in males by sagittal crest present, in females by total length
less than 238 and tooth-rows longer than, instead of about same
length as, tympanic bulla; from _M. e. streatori_, in both sexes,
by black tip of tail more than half of length of tail-vertebrae,
in males hind foot more than 33.7, tympanic bulla longer than,
instead of about same length as, upper tooth-rows; weight of skull
more than 1-1/4 grams, in females weight of skull more than 0.7
grams, length of lateral side of P4, 4 mm. or more; from _M. e.
olympica_, in males, length of hind foot more than 33, black tip
of tail more than 36.5 mm., weight of skull more than 1.2 grams,
basilar length more than 33.5, in females length of hind foot more
than 25.5, weight of skull more than 0.66 grams, basilar length
more than 28.4; from _M. e. gulosa_, in both sexes, by anterior
margin of tympanic bulla projecting below floor of braincase
rather than flush with squamosal (the difference is slight in
females), in males hind foot more than 33.5, weight of skull more
than 1-1/4 grams, basilar length more than 33.9, in females by
total length more than 222, hind foot longer than 26, weight of
skull more than 0.7 grams, basilar length more than 29.

_Description.--Size._--Male: Seven adult topotypes yield average
and extreme measurements as follows: Total length, 278 (249-305);
length of tail, 77 (69-81); length of hind foot, 36.5 (34-40). A
male topotype of unknown age weighed 113 grams.

Female: Two adult topotypes, with actual measurements in
parentheses, average as follows: Total length, 232 (228-236);
length of tail, 60 (57-62); length of hind foot, 27 (27-27). An
adult from Morovitz Guard Station, Wash., weighed 54 grams.

_Color._--Winter pelage rarely white, brown pelage
indistinguishable from summer pelage except for slightly more
smoky tinge in winter in specimens from some localities; otherwise
as described in _Mustela erminea streatori_ except that least
width of color of underparts averaging, in seven adult topotypes,
18 (0-37) per cent of greatest width of color of upper parts.
Black tip of tail averaging, in same series, 45 (38-52) mm. which
is 58 (53-65) per cent of length of tail-vertebrae.

In comparison with _richardsonii_ and _invicta_, _fallenda_
differs in darker color of upper parts and their extension at the
expense of the light-colored underparts which are narrower by a
half. In correlation with this restriction in area of the
light-colored underparts, the upper lips are brown instead of
white. In comparison with _anguinae_, _olympica_ and _streatori_,
the longer black tip on the tail is the principal difference in
color. From _gulosa_, _fallenda_ differs in slightly darker color
of upper parts and in narrow underparts, the width of the same
being only about a fifth instead of a third of the width of the
dark-colored upper parts.

_Skull._--Male (based on 7 adults): See measurements and plates
5-7. As described in _Mustela erminea richardsonii_ except that:
Weight, 1.5 (1.3-1.7) grams; basilar length, 35.7 (34.3-38.2).

Female (based on 6 ads.): See measurements and plates 11-13. As
described in _Mustela erminea richardsonii_ except that: Weight,
0.85 (0.73-1.0) grams; basilar length, 30.6 (29.4-31.7); breadth
of rostrum more than 30 per cent of basilar length.

In comparison with _richardsonii_, skulls of males differ as follows: averaging smaller in every measurement taken with no overlap in several dimensions; 40 per cent lighter; in relation to basilar length, rostrum (orbitonasal length) longer and skull slightly broader interorbitally. Females average smaller in every cranial and dental measurement taken with no overlap in basilar length, length of tooth-rows and length of tympanic bulla; 22 per cent lighter; breadth of rostrum more, rather than less, than 30 per cent of basilar length; in relation to basilar length, pre-and interorbital parts of skull larger, and mastoid breadth more.

Differences from males of _olympica_ are: size larger with no overlap in most measurements; 50 per cent heavier; tympanic bullae longer than upper tooth-rows rather than of about equal length; in relation to basilar length, rostrum shorter, braincase wider and deeper, zygomata more expanded. Females are larger with no overlap in most measurements; 35 per cent heavier; in relation to basilar length, pre-and interorbital regions narrower, braincase deeper and wider across mastoids.

Differences from _streatori_, in males, are: skull averaging larger in every cranial and dental measurement taken; 36 per cent heavier; tympanic bulla longer than, instead of about same length as, upper tooth-rows. In females the inner lobe of M1 is shorter anteroposteriorly; otherwise all measurements of _fallenda_ average larger and it is 33 per cent heavier; rostrum and interorbital region broader in relation to remainder of skull.

In comparison with _gulosa_, skulls of males differ as follows: averaging larger in every measurement taken with no overlap in several dimensions; 50 per cent heavier; tympanic bullae with anterior margins projecting slightly below squamosals rather than flush with same; length of bulla more than, rather than about same as, that of upper tooth-rows. Considering the great difference in size, the relative proportions are remarkably alike. In females, length of inner lobe of M1 about the same; otherwise averaging larger in every measurement taken; 44 per cent lighter; relative to basilar length, tooth-rows longer, skull wider across zygomata and mastoids, rostrum and interorbital regions slightly narrower, skull shallower in plane of last upper molars.

Comparisons with _haidarum_, _invicta_ and _anguinae_ are made in accounts of those subspecies.

_Remarks._--Until the name _fallenda_ was proposed in the course of the present study, most of the specimens of this race were assigned to _streatori_.

Intergradation with _streatori_ is complete as it is also with _invicta_ and _richardsonii_, in other words with each of the subspecies whose ranges meet that of _fallenda_. In color and in size the difference is least between _streatori_ and _fallenda_. As between _fallenda_ and _invicta_ the size is not greatly different and the intergradation in color is gradual. Between _fallenda_ and _richardsonii_ intergradation is somewhat different and to fully appreciate its nature we should remember that the color of _fallenda_ resembles that of the saturate coastal races, _streatori_, _anguinae_ and _olympica_ although the black tip of the tail is longer. In this latter feature and in several cranial details, as well as in greater degree of secondary sexual variation in size, _fallenda_ resembles _richardsonii_. Because the two differ more than do most subspecies of ermine whose ranges meet, some of the intergrades at first inspection appear to be widely different from either parent stock. For example, specimens from Alta Lake, British Columbia, may give this impression because the combination of large size and dark color suggests a kind of ermine different from either _fallenda_ or _richardsonii_. In no instance, however, has there been found in these intergrades any character other than those occurring in one or the other of the two parent races.

Along the coast in the north part of the geographic range assigned to _fallenda_, some specimens nearly typical of _richardsonii_ have been taken so near to the place where fairly typical _fallenda_ was obtained that I have doubted whether there is intergradation in the usual fashion in this area; more specimens will have to be obtained from this coastal area to resolve the doubt one way or the other.

The winter pelage is brown in all specimens at most localities. The only white pelage seen was in each of three specimens from Glacier, Whatcom County, Washington. A fourth specimen from there is in brown winter pelage. At any one locality there is much variation in the degree to which the dark color of the upper parts encroaches on the area that in most other races is light-colored. An extreme degree of encroachment is shown by a specimen taken on December 1, 1935, by R. A. Cummings, at Vancouver, British Columbia, in which the light color occurs only in three restricted areas, the chin, the throat and the lower breast; otherwise the coat is brown. There are other specimens, for instance from the type locality, which differ mainly in having an additional white spot in the inguinal region. The opposite extreme, in a specimen also from the type locality, is where the least width of the light-colored underparts on the abdominal region is a third of the circumference of the body. The two extremes are connected by a dozen intermediate stages. Of 64 specimens in which the color of the lips was carefully examined, one, from Vancouver, has both the upper and lower-lips brown; 9 have both the upper and lower-lips white; and 54 have the upper lips brown and the lower lips white.

_Specimens examined._--Total number, 72, arranged by localities
from north to south. Unless otherwise indicated, specimens are in
the National Museum of Canada.

=British Columbia.= Horseshoe Lake, Stillwater, 2; Vancouver,
1[74]; Point Grey, 1[31]; Port Moody, 5[91]; Chilliwack, 8 (2[75],
4[91], 1[60]); Sumas, 19 (18[75], 1[60]); Thurstons Ranch, 2;
Cultus Lake, 2; Mt. Baker Range, 5[75]; Lihumption Park, 1;
Huntingdon, 14; Tami Hy Creek, 1.

=Washington.= _Whatcom County_: Semiahmoo, 1[91]; New Whatcom,
1[68]; Lake Whatcom, 2[91]; 5 mi. W Glacier, 1[51]; Glacier (3 at
900 ft.), 4[91]; E Side Easton Glacier, Mt. Baker, 1[55]; Morovitz
Guard Station, 831 ft., 1[55].

=Mustela erminea olympica= Hall

Ermine

Plates 5, 6, 7, 12, 13 and 14

_Mustela erminea olympica_ Hall, Journ. Mamm., 26:81, February 27,
1945; Hall, Journ. Mamm., 26:181, July 19, 1945.

_Mustela rixosa_, Svihla and Svihla, Murrelet, 13:24, January,
1932.

_Mustela rixosa rixosa_, Svihla and Svihla, Murrelet, 14:39, May,
1933.

_Type._--Male, adult, skull and skin; no. 90738, U. S. Nat. Mus.,
Biol. Surv. Coll.; near head of Soleduc River, 4500 ft., Olympic
Mountains, Clallam County, Washington; April 28, 1897; obtained by
Vernon Bailey, original no. 6213.

The skin is well prepared and in good condition. The skull (plates
5-7) is unbroken and the teeth all are present and entire.

_Range._--Olympic Peninsula, Washington, south to Olympia. See
figures 25, 27 on pages 95, 149.

_Characters for ready recognition._--Differs from _M. e.
anguinae_, in males, by lesser average size, hind foot ordinarily
less than 33.4, and interorbital breadth ordinarily less than 8.5,
in females by smaller size, total length less than 235, tail less
than 65, hind foot less than 27.5, basilar length less than 30.2;
from _M. e. fallenda_, in males, by length of hind foot less than
33, black tip of tail less than 36.5, weight of skull less than
1.2 grams, basilar length less than 33.5, in females length of
hind foot less than 25.5, weight of skull less than 0.6 grams,
basilar length less than 28.4; from _M. e. streatori_ by smaller
size, in males hind foot less than 33.0, basilar length ordinarily
less than 32.5, in females by hind foot ordinarily not longer than
24, by breadth of rostrum less than 8.6, depth of braincase at
posterior border of upper molars less than 7.6.

_Description._--_Size._--Male: Twelve individuals of adult
proportions yield average and extreme measurements as follows:
Total length, 243 (205-269); length of tail, 65 (60-74); length of
hind foot, 31 (29-32).

Female: Corresponding measurements of six females are: 196
(188-208), 52 (45-60?), 23.4 (22.7-24.0). An adult weighs 30
grams.

_Color._--As described in _Mustela erminea streatori_ except that
least width of color of underparts averaging, in 12 males of adult
proportions, 5 (0-11) per cent of greatest width of color of upper
parts. Black tip of tail averaging, in same series, 26 (20-35)
mm., which is 40 (31-58) per cent (average the same as in
_streatori_) of length of tail-vertebrae.

_Skull._--Male (based on 5 adults): See measurements and plates
5-7. As described in _Mustela erminea richardsonii_ except that:
Weight, 1.0 (0.9-1.1) grams; basilar length, 31.8 (30.6-32.5);
length of tooth-rows more or less than (about equal to) length of
tympanic bulla.

Female (illustrated by 3 adults): See measurements and plates
12-14. As described in _Mustela erminea richardsonii_ except that:
Weight, 0.55 (0.52-0.58) grams; basilar length, 27.1 (26.7-27.5);
breadth of rostrum more than 30 per cent of basilar length.

In comparison with _streatori_, skulls of corresponding sex average smaller in every measurement taken with no overlap in most of those of females. Exception is to be made for the inner lobe of M1 in males where the size is the same. By weight males are smaller by 10 per cent and females by 14 per cent. In relation to other parts of the skull the tympanic bullae are narrower and in females they are shorter as well. Comparison with _anguinae_ and _fallenda_ has been made in the accounts of those subspecies.

_Remarks._--The smaller size, especially of females, is the principal feature distinguishing this race from _streatori_. On the basis of available data the female of _olympica_ is smaller than that of any other race and hence is the smallest adult weasel of the species _erminea_, in either the Old World or in America.

Intergradation with _streatori_ is indicated by specimens from the southern end of Puget Sound. These specimens are intermediate in size between typical examples of the two races concerned.