Chapter I: Part 1

THE
ZOOLOGY
OF
THE VOYAGE OF H.M.S. BEAGLE,
UNDER THE COMMAND OF CAPTAIN FITZROY, R.N.,
DURING THE YEARS
1832 TO 1836.

_PUBLISHED WITH THE APPROVAL OF
THE LORDS COMMISSIONERS OF HER MAJESTY’S TREASURY._

=Edited and Superintended by=

CHARLES DARWIN, ESQ., M.A., F.R.S., V.P.G.S.,
NATURALIST TO THE EXPEDITION.

PART V.

REPTILES,

BY
THOMAS BELL, ESQ., F.R.S., F.L.S., &c.
PROFESSOR OF ZOOLOGY IN KING’S COLLEGE.

LONDON:
PUBLISHED BY SMITH, ELDER AND CO., 65, CORNHILL.
MDCCCXLIII.

London:
Printed by STEWART and MURRAY,
Old Bailey.

REPTILIA.

=Described by=

THOMAS BELL, ESQ., F.R.S., F.L.S., ETC.

ILLUSTRATED BY NUMEROUS ENGRAVINGS.

PREFACE.

Amongst the Reptiles and Amphibians obtained by Mr. Darwin, in the Voyage of the Beagle, there are several of great interest, not merely on account of their novelty as newly discovered species, of which there are nearly thirty, or as forming the types of genera not previously known, or of any remarkable peculiarity of form, structure, or habit, although in all these respects many of them are highly interesting; but more particularly as serving to establish or confirm several points connected with their geographical distribution.

From the structure of most of these animals and their consequent habits of life, circumscribed as they are for the most part in their locomotive powers, it might reasonably be predicated that they would, upon the whole, exhibit as distinct examples of restriction, with regard to their geographical boundaries, as any class of vertebrated animals; and that the intervention of seas and of mountains would be sufficient to limit the range of a species. Such is in fact usually the case; and not only is the same species not found in the Old and New Continents, but, with very few exceptions, not even on the opposite sides of the South American Continent, in which range Mr. Darwin’s discoveries have principally been made. The occurrence, however, of _Bufo Chilensis_ at Rio Janeiro and at Buenos Ayres on the eastern, and at Valparaiso and the Archipelago of Chonos on the western side of the continent, shows an extent of distribution exceedingly unusual if not absolutely unparalleled in this family. It is, however, still possible that further and more extended researches into the characters of the animals in question, and an examination of individuals from each locality at various ages, may prove that there are two species, which have been confounded with each other, and the anomaly may thus be removed.

But although the circumscribed range of a species may be accounted for by the reasons above mentioned, and others of a restrictive nature, it is not so easy to refer to any known or obvious cause the remarkable fact of a whole genus, consisting of numerous species, being thus geographically limited. Yet this is a well-known and very common circumstance with regard to several groups of animals. In our present researches there exists a remarkable example of this fact in the genus _Proctotretus_, consisting, as is now known, of at least fourteen species, all inhabiting the western coast of South America. These facts, interesting as they are, have never been sufficiently investigated, although, it must be confessed, there are so many anomalies in relation to this subject, that we must despair of ever reducing the facts in question to any thing like fixed laws.

The close approximation of the Raniform and Hyliform groups of the Anourous Amphibia is strikingly illustrated by several new forms obtained by Mr. Darwin, which are so perfectly osculant between the two families, that it is difficult to assign them a decided location. And the addition of some bufonine forms in the family _Ranidæ_, as at present constituted, and on the other hand of some amongst the _Bufonidæ_, which are no less raniform in their general structure and habits, render it increasingly probable that the single character of the presence or absence of superior maxillary teeth, must be considered as insufficient to constitute alone a natural distinctive family character. There are several minor points bearing upon the natural arrangement of the Anourous Amphibians, which are illustrated by the characters of some of the species now first described, which will doubtless at some future time assist in the construction of a classification of these animals, bearing at least a nearer approximation to their natural arrangement than any that has hitherto been promulgated.

The Ophidians have been placed in the hands of Mons. Bibron, who is at the present time engaged in completing his admirable history of Reptiles, by the publication of those volumes which are devoted to this order; and it must be considered a fortunate circumstance that the delay which has taken place in the appearance of that portion of his labours, has thus afforded the opportunity of embodying in so perfect a work, the numerous discoveries of Mr. Darwin in this particular department of Erpetology.

T. B.

_Hornsey, Sept. 2, 1843._

LIST OF SPECIES.

PAGE
Alsodes monticola 41
Amblyrynchus cristatus 23
—— Demarlii 22
Ameiva longicauda 28
Batrachyla leptopus 43
Borborocætes Bibronii 35
—— Grayii 36
Bufo Chilensis 49
Centrura flagellifer 25
Cyclodus Casuarinæ 30
Cystignathus Georgianus 33
Diplolæmus Bibronii 21
—— Darwinii 20
Gerrhosaurus sepiformis 29
Gymnodactylus Gaudichaudii 26
Hyla agrestis 46
—— Vauterii 45
Hylorina sylvatica 44
Leiocephalus Grayii 24
Leiuperus salarius 39
Limnocharis fuscus 33
Litoria glandulosa 42
Naultinus Grayii 27
Phryniscus nigricans 49
Pleurodema bufoninum 39
—— Darwinii 36
—— elegans 37
Proctotretus Bibronii 6
—— Chilensis 2
—— cyanogaster 12
—— Darwinii 14
—— Fitzingerii 11
—— gracilis 4
—— Kingii 13
—— multimaculatus 17
—— nigromaculatus 10
—— pectinatus 18
—— pictus 5
—— signifer 8
—— tenuis 7
—— Weigmannii 15
Pyxicephalus Americanus 40
Rana Delalandii 31
—— Mascariensis 32
Rhinoderma Darwinii 48
Uperodon ornatum 50

LIST OF PLATES.

Plate I.│Proctotretus Chilensis.
„ │—— gracilis.
────────┼───────────────────────────
II.│—— pictus.
────────┼───────────────────────────
III.│—— Bibronii.
„ │—— tenuis.
────────┼───────────────────────────
IV.│—— signifer.
„ │—— nigromaculatus.
────────┼───────────────────────────
V.│—— Fitzingerii.
„ │—— cyanogaster.
────────┼───────────────────────────
VI.│—— Kingii.
────────┼───────────────────────────
VII.│—— Darwinii.
────────┼───────────────────────────
VIII.│—— Weigmannii.
────────┼───────────────────────────
IX.│—— multimaculatus.
„ │—— pectinatus.
────────┼───────────────────────────
X.│Diplolæmus Darwinii.
────────┼───────────────────────────
XI.│—— Bibronii.
────────┼───────────────────────────
XII.│Amblyrynchus Demarlii.
────────┼───────────────────────────
XIII.│Gymnodactylus Gaudichaudii.
„ │Naultinus Grayii.
────────┼───────────────────────────
XIV.│Leiocephalus Grayii.
„ │Centrura flagellifer.
────────┼───────────────────────────
XV.│Ameiva longicauda.
„ │Gerrhosaurus sepiformis.
„ │Cyclodus Casuarinæ.
────────┼───────────────────────────
XVI.│Rana Delalandii.
„ │—— Mascariensis.
„ │Limnochans fuscus.
„ │Cystignathus Georgianus.
────────┼───────────────────────────
XVII.│Borborocœtes Bibronii.
„ │—— Grayii.
„ │Pleurodema Darwinii.
„ │—— elegans.
„ │—— bufoninum.
────────┼───────────────────────────
XVIII.│Leiuperus salarius.
„ │Pyxicephalus Americanus.
„ │Alsodes monticola.
„ │Litoria glandulosa.
„ │Batrachyla leptopus.
────────┼───────────────────────────
XIX.│Hylorina sylvatica.
„ │Hyla agrestis.
„ │—— Vauterii.
────────┼───────────────────────────
XX.│Rhinoderma Darwinii.
„ │Phryniscus nigricans,
„ │Uperodon ornatum.

ERRATA.—In Plate XIX. for “Hylonia” read “Hylorina.”
_for_ “vanterii” _read_ “Vauterii.”

REPTILES.

TRIBUS—EUNOTES. _Bibron._
FAMILIA—TROPIDURIDÆ. _Mihi._
TROPIDOLEPIDIENS. _Bibr._
GENUS—Tropidurus. (In part.) _Weigmann._
PROCTOTRETUS. _Bibr._

CHARACTER GENERICUS.—_Pori femorales_ nulli. _Pori præ-anales_ in
maribus tantùm. _Cristâ dorsalis_ nulla. _Dentes palatini._ _Squamæ_
imbricatæ; _dorsales_ carinatæ.

The genus which I take the present favourable opportunity to illustrate, formed a section or sub-genus of the genus _Tropidurus_, according to Weigmann, who, however, was acquainted with two species only; _Pr. Chilensis_ and _Pr. nigromaculatus_. Of the varieties of the former of these, that author has made no less than three species ; but these have been very properly reduced by M. Bibron to one only. The last-named excellent erpetologist described several additional species, which had been brought from Chile, by M. D’Orbigny, and others ; and I received, some years since, from Capt. King, three or four species which were found by him in the same locality, in the course of his well-known survey. The number of species altogether, hitherto known, amounts to ten; to which I have now the opportunity of adding four entirely new, forming part of the interesting collection of Reptilia made by Mr. Darwin. One of them, _Pr. Kingii_, was already in my collection, amongst those which were given me by Capt. King. The genus, therefore, of which, but lately, two species only were known, now consists of fourteen ; and it is highly probable that more may yet be obtained by more prolonged and extensive investigation in the same districts.

Thus of the species now described two were known to Weigmann, and described by him, namely, _Chilensis_, and _nigromaculatus_. I received from Capt. King, _Chilensis_, _pictus_, _cyanogaster_, _Kingii_, _Fitzingerii_, and, from other sources, _Chilensis_, _pictus_, _Weigmannii_. Bibron describes the whole of these, excepting _Kingii_, and in addition to them _tenuis_, _pectinatus_, _signifer_. In Mr. Darwin’s collection are found all those described by Bibron, excepting _signifer_; and in addition _Kingii_ now first described, and the following species never before observed, namely, _Darwinii_, _gracilis_, _Bibronii_.

Although the form of the whole of the species much more nearly approximates that of the Agamidæ than most others, they are far removed from that family by several important characters, which it is unnecessary here to detail.

PROCTOTRETUS CHILENSIS.

PLATE I.—FIG. 1.

_Auribus margine anteriore dentato; collo non plicato; squamis dorsi
magnis, rhombeis; acutè carinatis; serie unicâ squamarum
supralabialium._

_Calotes Chilensis_, Less, et Garn. Voy. de la Coquille, Zool. Rep. t. i. f. 2. _Tropidurus Chilensis_, Weigm. Act. Acad. Cæs. Leop. Carol. Nat. cur. xvii. pp. 233. 268. _Proctotretus Chilensis_, Bibr. Hist. Nat. des Rep. IV. p. 269. Sun. _Tropidurus nitidus_, Weigm. l. c. p. 234, t. xvii. f. 2. Var. _Tr. olivaceus_, Ib. l. c. p. 268.

Habitat, Guasco in Northern Chile.

DESCRIPTION.—Head short and broad, rostrum rounded, obtuse. Scales of
the head large, and slightly raised, separated by distinct
grooves. Superciliary ridge strongly marked, forming a distinct
carina, composed of five or six narrow, elongated, obliquely
imbricated scales. Nostrils large, nearly round. A single series
of narrow scales between those of the upper lip and the orbit.
Scales of the temples imbricated, rhomboidal and carinated. The
opening of the ear oval, rather large, furnished anteriorly with
three or four projecting scales, of which the upper one is the
largest. The neck is short, robust and round, and without any
lateral fold; in which it differs from every other species of the
genus. The trunk is thick, rounded on the back and sides,
flattened beneath, diminishing toward either extremity. The tail
is ordinarily almost twice as long as the body, thick at its
origin, and tapering regularly to the extremity, nearly round,
excepting near the base, where it is slightly quadrilateral. The
anterior feet when placed against the sides, extend backwards
little more than mid-way between the shoulder and the groin; the
posterior ones, stretched forward, reach the arm-pit.

The scales of the whole upper and lateral parts of the body, tail,
and limbs, are loosely imbricated, large, rhomboidal, and
furnished with an elevated carina, terminating in an acute point:
those of the under parts are large, smooth, and obtuse.

This is one of the most beautiful species of the genus. The
general form is robust and solid, forming a remarkable contrast
with most other species of the genus. The surface is beautifully
relieved by the fine, large and prominent scales, which are ranged
in rows of perfect regularity, of which there are about eighteen
on the back and side.

In colour and markings the individuals differ considerably; so as
to have given rise to the opinion that they form three distinct
species. Monsieur Bibron mentions two principal varieties,
constituting the _Tropidurus olivaceus_ and _Tr. Chilensis_ of
Weigmann. In the former, the colour is of a more or less bronzed
bright green, or yellowish, according as the green or yellow
colour prevails on the scales, each of which is green, with a
border of yellow on each side: this border, according to M.
Bibron, in some individuals of a blood-red colour. In some,
especially in young individuals, there are several waved bands
running transversely across the back.

In the second variety, says M. Bibron, the upper parts are either
of an olive colour, with a golden glance in certain lights, or
fulvous, with more or less of a yellow tint; and these have always
four brown bands running the length of the body, appearing as if
formed of a series of large spots united together. “The temples
are marked with a black line, which extends from the posterior
angle of the eye to the ear; another divides behind the occiput
into two branches, which pass to the neck there to join the dorsal
bands.” There are other variations of colour, but scarcely
deserving to be considered as constituting permanent or fixed
varieties; the largest and finest specimen I have seen, which I
received from Chile, is almost uniformly of a fine metallic green,
without any markings.

DIMENSIONS.
Inches. Lines.
Length of the head 0 9
of the body 3 5
of the tail 6 0
────────────────────────────────────────────
Total length 10 4
Length of anterior extremity 2 0
of posterior extremity 1 2

This species would appear to be very common in Chile, from the numerous specimens from that country in the museum in Paris, which were brought by M. Gay, and by M. D’Orbigny. I have also received specimens from Capt. King. I find only one or two specimens in Mr. Darwin’s collection, which he found at Guasco in Chile.

PROCTOTRETUS GRACILIS. N.S.

PLATE I.—FIG. 2.

_Corpore gracili: capitis squamis lævibus, non imbricatis: aurium
margine anteriore minutè bi-tridentato: collo vix plicato, squamis
imbricatis: serie unicâ squamarun supralabialium: femorum facie
posteriore omninò granulosâ._

Habitat, Port Desire, Patagonia. Mr. Darwin, MS.

DESCRIPTION.—This new species is more slender and graceful in its
general form than any other of the genus, not excepting _Pr.
tenuis_, which in its general proportions it considerably
resembles. The head is rather short, the anterior portion
including the eyes being nearly an equilateral triangle. The
muzzle is rounded. The scales of the head flat, rather large,
consisting behind the nose of three series of 2, 3, 3, and 2,
mostly hexagons. The nostrils are small and perfectly round, the
superciliary ridge is very slightly marked; there is but a single
row of small linear scales between the labial and suborbitar. The
ear is of moderate size, the anterior margin having two or three
small projecting scales. The scales on the temples are imbricated
and smooth; those of the sides of the neck also imbricated but
very small. The neck is almost wholly without a fold, having
merely a slight loose elevation of the skin. The scales of the
back are small, rhomboidal, flat, the carina low, and not pointed
at the extremity. They consist of about ten rows on each side of
the median line. Those of the sides and belly are wholly without
any notch on the free margin. The scales around the axillæ, and
those of the posterior face of the thighs are granular. The tail
is of considerable length, being more than twice the length of the
head and body. The limbs are remarkably long; the anterior, when
pressed against the side, reaching to the setting on of the thigh,
and the posterior reaching forwards nearly to the ear. The general
colour of the upper parts is greyish brown, with a yellow
longitudinal fascia extending on each side from the upper edge of
the orbit to some distance along the tail—and another from beneath
the eye to the thigh. The middle of the back is lighter than the
sides—beneath the second lateral line the colour fades, and on the
belly it is pale buff or light yellow. The sides are dotted with
black; and there are some dark waved lines and dots beneath the
lower jaw.

This species is at once distinguished from every other by the fold
of the neck being scarcely cognizable. It is however not so
absolutely wanting as in _Pr. Chilensis_.

DIMENSIONS.
Inches. Lines.
Length of the head 0 5
of the body 1 4
of the tail 3 8
────────────────────────────────────────────
Total length 5 7
Length of anterior extremity 0 7
of posterior extremity 1 1

A single individual of this species was taken by Mr. Darwin at Port Desire.

_Plate 1._

_Drawn from Nature by B. Waterhouse Hawkins, on stone in Lithotint C.
Hullmandel’s Patent._
]

_1. Proctotretus Chilensis_ _Nat. Size._
_2. ____ gracilis_ „
────────────────────────────────────────
_1a._ _1b._ _Magnified
views._
_2a._ „

_Plate 2._

_Drawn from Nature by B. Waterhouse Hawkins,
on stone in Lithotint C. Hullmandel’s Patent._
]

_1. 2. Proctotretus pictus._ _Nat. Size._

PROCTOTRETUS PICTUS.

PLATE II.—FIG. 1, 2.

_Capite squamis parvis, lævibus, non imbricatis; aurium margine
anteriore granuloso; serie unicâ squamarum supralabialium; squamis
temporum subcarinatis, imbricatis; collo ad latera granuloso;
squamis dorsalibus parvis, rhombeis, carinâ humili, posticè obtusâ;
facie posteriore femorum omninò granulosâ._

_Proctotretus pictus_, Bibr. l. c. p. 276.

Habitat, Chile.

DESCRIPTION.—This species is moderately slender in its general form,
but more fusiform than _Pr. tenuis_, which it much resembles in
many of its characters. The head, which is rather short, and with
the snout rounded, is covered with numerous small flat plates
which vary exceedingly in their form and arrangement. The upper
surface of the head is flattened, and the superciliary ridges
distinctly marked. The temples are covered with small flat scales,
which are slightly imbricated and carinated. The sides of the neck
are granulated; and the anterior margin of the auditory cavity has
small simple granulations. The scales of the back are
distinguished from those of many other species by the flatness of
the carina which is also obtuse posteriorly; they are small and
closely imbricated. Those of the sides are almost without any
carina, and those of the belly and throat small and very smooth,
and the whole of them entire. The upper parts of the limbs are
covered with scales similar to those of the back, but smaller.
Those of the under part of the fore arm are similar, but beneath
the thighs they are smooth and on the posterior part of the thighs
they are wholly granular. The tail is furnished with quadrilateral
carinated scales disposed in whorls. The margin of the cloaca has
from two to four pores.

The colour of this species varies greatly. Bibron has enumerated
three principal varieties, of which I have several specimens,
which were brought home and presented to me by Capt. King, who
obtained them during his survey of the coast of South America.
These varieties, however, occasionally run into each other.

Var. A. General colour of the upper part bronzed or coppery,
having a green longitudinal line on each side of the back, at the
inner margin of which is a series of very distinct black dots. The
sides of the neck and body are of a similar colour to the back,
with indistinct black spots; beneath this part the ground colour
becomes blue with black dots. The throat is blackish, and the
inferior surface generally is very pale bluish green.

Var. B. This variety is described by M. Bibron as of a brown
colour more or less dotted with yellow, and having a line of that
colour along each side of the back, extending from the posterior
angle of the eye to the base of the tail, and having on each side
a series of angular black spots. Some of these spots on the upper
part of the flanks, become dilated, so as to form a sort of
vertical or transverse waved bands, with yellowish margins. On the
neck there are small black lines, and the upper part of the head
is brown with blackish spots. The upper surface of the legs and of
the tail is brown with transverse bands composed of black dots.
The whole under surface is of a whitish colour, sometimes having a
slight tint of orange towards the posterior parts, marbled with
black.

Var. C. In this variety the general colour is dark brown, and the
yellow or green longitudinal lines which characterize the former
varieties are but slightly marked; but the black spots unite and
form irregular transverse bands.

DIMENSIONS.
Inches. Lines.
Length of the head 0 6
of the body 1 8
of the tail 4 6
─────────────────────────────────
7 0

This specimen very much resembles in its more tangible characters, the _Pr. tenuis_; from which, however, it differs totally in the colouring, and in some measure also in the general form, which is more thick and robust.

Found in Chile by M. Gay, from whence I also received specimens from Capt. King, and other sources.—“Valparaiso.” Mr. Darwin.

PROCTOTRETUS BIBRONII. N.S.

PLATE III.—FIG. I.

_Capite squamis lævibus, subconvexis; auribus ovalibus, margine
anteriore unidentato; squamis temporum collique rotundatis lævibus
imbricatis; colli minimis; serie unicâ squamarum supralabialium;
squamis dorsi rhomboideis, carinatis, posticè acuminatis; abdominis
squamis omnibus integris; femorum facie posteriori omninò
granulosâ._

Habitat, Port Desire. Mr. Darwin.

DESCRIPTION.—General form resembling that of _Pr. pictus_ and
_cyanogaster_. Head moderately short, obtuse, covered with rather
large slightly convex scales; a single row of scales between the
labial and the orbitar. The anterior margin of the ear has a
single tooth. The temples and the sides of the neck are covered
with imbricated scales, which have no carina—those of the neck,
especially those on the fold of the skin are smaller and more
raised than the others. The scales of the back are rather large,
rhomboidal, with a distinct carina, terminating in a point. Those
of the abdomen and sides are all of them entire at the margin. The
posterior surface of the thighs is wholly granular.

The only specimen obtained being a female, the number of pre-anal
pores is not known.

The general colour of this species is brownish grey; a black
longitudinal line runs down the middle of the back and tail. There
are two series of black spots on each side, and a small
interrupted fascia of the same colour extends from the shoulder to
the thigh. The belly is of an uniform dirty white.

_Plate 3._

_From Nature by B. Waterhouse Hawkins
in Lithotint C. Hullmandel’s Patent._
]

_1. Proctotretus_ _Bibronii_ │_Nat. Size._ _2._ _tenuis_ │ „ _a & b._ _1 & 2._ _Magnified Views of Heads._

This species approaches considerably to _Pr. cyanogaster_ in general form and habit, and in many of its characters; but it may be at once distinguished from it not only by its colouring, but by the absence of even the slightest appearance of a carina on any of the scales of the temples or of the sides of the neck.

DIMENSIONS.
Inches. Lines.
Length of the head 0 6
of the body 1 6
of the tail 3 4
────────────────────────────────────────────
Total length 5 6
Length of anterior extremity 0 7
of posterior extremity 1 1

Found by Mr. Darwin at Port Desire, in Patagonia.

PROCTOTRETUS TENUIS.

PLATE III.—FIG. 2.

_Capite squamis lævibus, non imbricatis; auribus magnis, margine
anteriore subtuberculato; serie unicâ squamarum supralabialium;
temporibus squamis rotundatis, imbricatis; collo granuloso; squamis
dorsi parvis, obtusis, carinis minimis; squamis lateralibus exiguis,
non imbricatis; facie posteriore femorum omninò granulosâ._

_Proctotretus tenuis_, Bibr. l. c. p. 279.

DESCRIPTION.—General form slender: head rather short and obtuse,
covered with flattened smooth scales; anterior margin of the ears
with one or more slight tubercles; temples covered with rounded
imbricated scales, some of which are slightly carinated; sides of
the neck, and above the shoulders granular; scales of the back
small, slightly carinated, obtuse; those of the sides very small,
very little imbricated; those of the belly small and smooth. The
posterior surface of the thighs has no patch of imbricated scales,
but is wholly granular.

The colour of the two specimens brought home by Mr. Darwin is so
much obliterated, that I am obliged to have recourse to the
account given by Bibron of the colour and markings of this
species:— “Les deux sexes du _Proctotréte svelte_ n’ont pas le
même mode de coloration. Ni l’un ni l’autre ne portent, de chaque
côté du dos, une bande longitudinale verte ou jaunâtre comme cela
s’observe dans l’espèce précédente, (_Pr. pictus_.)

“Le mâle a le dessus de la tête nuancé de brun et de fauve, ou
bien ponctué de jaune et de noirâtre. La région cervicale est,
ainsi que le dos, vermiculée de noir sur un fond brun, qui est
lui-même semé de taches, soit bleuâtres, soit verdâtres, on
ardoisées; quelquefois même on en remarque de jaunâtres. Presque
tous les individus ont les côtés du cou marqués chaqun d’une raie
noire qui s’étend depuis le haut de l’oreille jusqu’à l’épaule.
Les membres et la queue sont coupés en travers par des bandes
onduleuses noirâtres, dont les intervalles se trouvent remplis par
de taches, les unes bleuâtres, les autres de la couleur du cuivre
rouge, la gorge tantot est jaune, tantot d’un beau vert
métallique. Souvent elle est, de même que les autres régions
inférieures de l’animal, vermiculée de gris-brun pâle sur un fond
blanchâtres, glacé de violet.

“La femelle a toutes ses parties supérieures peintes d’un
gris-brun fauve. Son cou et son dos portent deux séries parallèle
de demi-cercles noirs, ayant leur bord convexe tourné de coté de
la tête, et leur bord concave liseré de blanchâtre, ou bien d’une
teinte plus claire que celle du fond de la couleur du dos. La
région moyenne de celuici est quelquefois ponctuée de noir, ou
tachetée de blanchâtre. Des lignes noires onduleuses traversent le
dessus de la queue dont le dessous est souvent cuivreux. Les
régions inférieures sont blanchâtres ou bien colorées de la même
manière que celles des individus mâles.”

Mr. Darwin’s only observation on the colour of this species is,
that it is “brownish black with transverse black bands.”

DIMENSIONS.
Inches. Lines.
Length of the head 0 5
of the body 1 6
of the tail 2 1
────────────────────────────────────────────
Total length 4 2
Length of anterior extremity 0 8
of posterior extremity 1 3

Found at Valparaiso, and at Concepcion, in Chile.

PROCTOTRETUS SIGNIFER.

PLATE IV.—FIG. 1.

_Capite brevi, obtuso, depresso, squamis lævibus planis; aurium
margine anteriore bi-tuberculato; squamis temporum imbricatis; colli
granulatis; serie unicâ squamarum supralabialium; squamis dorsi
laxis imbricatis, vix carinatis; facie posteriore femorum omninò
granulosâ. Dorso flavescenti-griseo, signis nigris, in seriebus
quatuor longitudinalibus dispositis._

_Proctotretus signifer_, Bibr. l. c. p. 288.

_Plate 4._

_Printed by C. Hullmandel._
]

_1._ _Proctotretus_ _signifer._
_2._ _nigromaculatus._
_2a._ _Magnified View._

Head short, depressed, somewhat abruptly deflexed from the vertex—the
scales flat, those of the suprà-orbital arch being numerous, and less
regular than in most other species. Between the labial scales, and the
long infra-orbital plate is a single series of rounded scales.[1] The
scales of the temples are rather large, somewhat rounded, slightly
imbricated, and a few of the posterior ones having the vestige of an
obtuse carina. The ear is rather small, the anterior margin having two
slightly prominent scales towards the lower part.

Footnote 1:

Mons. Bibron states that there are two series, but on examining his
specimen I find a single series only.

The body is depressed; the tail moderately long, thick and slightly
four-sided at the base, becoming much smaller and round towards the
middle. The scales of the sides of the neck are small and granular;
those of the upper parts of the body small, rhomboidal, rounded
posteriorly, loose, much imbricated, and with an extremely low and
inconspicuous carina. They are arranged in about twenty-two
longitudinal series. Those of the sides are larger and quite smooth.
The scales of the whole under part of the throat and belly are
rhomboidal, smooth and much imbricated; a very few towards the sides
of the abdomen are slightly notched at the apex. The under surface of
the anterior and the hinder surface of the posterior extremities are
covered with very fine granular scales; those of the upper surface of
the members being rhomboidal, smooth, but slightly carinated and
obtuse. The tail is covered with small rhomboidal scales which are
considerably imbricated and distinctly carinated. The scales of the
upper surface of the toes are smooth; those on their sides
uni-carinated, and those beneath tri-carinated and broad.

The general colour of the upper parts is a yellowish grey, with black
markings, which have somewhat the character, as Mons. Bibron observes,
of Arabic letters. On the neck and back these markings are disposed in
four longitudinal series; and there are small linear markings on the
upper part of the shoulders and thighs. The tail is similarly marked,
the under parts are whitish, with brown lines and spots.

DIMENSIONS.
Inches. Lines.
Length of the head 0 6
of the body 1 5
of the tail 3 0
────────────────────────────────────────────
Total length 5 1
Length of anterior extremity 0 8
of posterior extremity 1 2

This species is not found amongst the reptiles obtained by Mr. Darwin, but as it has never been figured, it appeared very desirable that this opportunity should not be lost. I am indebted to the great kindness of my friend M. Bibron for the loan of the only specimen which I have seen, and from which the accompanying figure is taken. It formed part of the zoological collections obtained by Mons. D’Orbigny for the French Museum.

PROCTOTRETUS NIGROMACULATUS.

PLATE IV.—FIG. 2.

_Capite brevi, squamis neque imbricatis nec carinatis, tecto; auribus
margine anteriore tridentato; serie unicâ squamarum supralabialium;
squamis temporum magnis, rotundatis, imbricatis; colli (et præcipuè
plicæ) crassis, elevatis; facie posteriore femorum omninò granulosâ;
squamis nonnullis ad latera abdominis gulæque emarginatis; maculâ
transversè; oblongâ, nigrâ, suprà regionem scapularem._

_Tropidurus (Leiolæmus) nigromaculatus_, Weigm. Act. Acad. Cæs. Nat. cur. xvii. p. 229. _Proctotretus nigromaculatus_, Bibr. l. c. p. 281.

Habitat, Coquimbo, Chile.

DESCRIPTION.—Head short, the muzzle rounded, rather obtuse; scales of
the upper part of the head somewhat convex, smooth; a single line
of scales between the labial and orbitar; ears rather large, the
anterior margin having three rather prominent scales, the middle
one being the largest. Temporal scales somewhat large, smooth,
rounded, and imbricated, those towards the upper part slightly
carinated; those of the sides of the neck thick and elevated,
those on the fold being rather acutely prominent; scales of the
back carinated, the carina terminating in an acute point; a few of
the scales at the sides of the abdomen and throat notched; the
remainder of the scales of the under parts rhomboidal. The scales
about the axilla and around the base of the shoulder are granular
and very small, as are those of the posterior surface of the
thighs, on which part there are no imbricated scales as in _Tr.
Fitzingerii_. The tail is round, excepting at the base where it is
slightly flattened; it is moderately long and slender. The
anterior extremity placed against the side does not reach to the
thigh; the posterior similarly placed reaches to the shoulder. The
colour of this species is yellowish grey above, with a yellowish
longitudinal line on each side the back, and two rows of black
spots each margined with yellow behind. There is a large and
distinct oblong black mark on the region of the scapula, from
which circumstance the species takes its name. On the posterior
surface of the thighs, towards the upper part, are three or four
black dots placed in a line. The under surface is yellowish white
with dark grey dots and lines under the chin and throat.

DIMENSIONS.
Inches. Lines.
Length of the head 0 5
of the body 1 5
of the tail 2 8
────────────────────────────────────────────
Total length 4 8
Length of anterior extremity 0 8
of posterior extremity 1 2

This species was first described by Weigmann, and subsequently by M. Bibron, from specimens obtained by Gaudichaud from Coquimbo, at which place the single specimen brought home by Mr. Darwin was also obtained.

_Plate 5._

_From Nature by B. Waterhouse Hawkins,
in Lithotint C. Hullmandel’s Patent._
]

_1._ _Proctotretus_ _Fitzingerii._│_Nat. Size._
_2._ _Cyanogaster_ │ „

PROCTOTRETUS FITZINGERII.

PLATE V.—FIG. 1.

_Capite squamis lævibus, non imbricatis; margine anteriore aurium
granuloso; squamis supralabialibus ovalibus, in serie unicâ
dispositis; squamis dorsalibus parum carinatis, posticè obtusis.
Facie posteriore femorum præcipuè granulosâ sed portione, caudam
versus, squamis majoribus, rhomboideis imbricatis tectâ._

_Proctotretus Fitzingerii_, Bibr. l. c. p. 286.

Habitat, Patagonia.

DESCRIPTION.—General form thick and robust, the head short being
nearly as broad as it is long. The muzzle slightly rounded. Scales
of the head flat, small and numerous. Two scales only behind the
rostral and between those which are pierced by the nostrils. Those
over the nose and around the occipital scales being larger and
more regularly arranged than the others. The ear is large, oval,
the anterior margin having, towards the upper part, about three
small, oval, granular, very slightly projecting scales. Temples
covered with small, rounded or slightly hexagonal scales, which
are scarcely imbricated. A single range of rather broad oval
scales between the orbit and the upper lip. Scales of the sides of
the neck, and above and behind the shoulder small, granular. The
trunk thick; scales of the back very small, imbricated, very
slightly carinated, and not pointed behind; those of the under
parts smooth and rhomboidal. The legs are short and robust. The
anterior pair, placed against the side do not extend backwards
more than halfway to the thigh. The posterior pair do not quite
reach the arms. The posterior face of the thighs is covered with
granular scales, excepting a large patch near the groin rising to
near the upper surface of the thigh, which are imbricated and
rhomboidal, similar to those of the inferior surface of the thigh.
The scales of the upper part of the toes are smooth, those beneath
have one or two slight carinæ.

This species varies very much in colour; three or four tolerably
distinct varieties may be noticed, but they often pass more or
less into each other. As I have only one of these varieties in my
possession, I quote the following description from Mons. Bibron’s
account of the specimens in the French Museum.

Var. A. Les parties supérieures sont grises, ou bien d’un brun
marron plus ou moins clair. Il règne au long du cou et du dos
quatre series de taches noires, bordées de blanc en arrière. La
queue et les membres offrent des bandes transversales anguleuse,
d’un teint marron noirâtre, alternant avec des bandes semblables
mais de couleur blanche. Les régions inférieures aussi sont
blanches, excepté la gorge, qui est parcourue par des raies
confluentes brunes. D’autres raies d’un brun marron sont imprimées
verticalement, sur les lèvres.

Var. B. Cette variété se distingue de la précédente, en ce que le
dessus de ses membres est ponctué de noirâtre, et que les quatre
séries de taches qui ornent le dos de la première variété sont
appliquées ici sur un fond fauve jaunâtre. Puis la gorge est
verdâtre et le ventre noir, marbré de blanc.

Var. C. Le dessus du corps est uniformement peint d’un vert olive. Le dessus du cou, le milieu de la poitrine et celui du ventre sont d’un noir profond.

DIMENSIONS.
Inches. Lines.
Length of the head 0 7
of the body 2 8
of the tail 4 2
────────────────────────────────────────────
Total length 7 7
Length of anterior extremity 1 2
of posterior extremity 2 0

This species agrees with _Pr. Darwinii_ and _Weigmannii_, and in some degree with _Pr. Kingii_, in having a portion of the posterior face of the thighs covered with imbricated scales. This is a character, which although existing in all those which I have named, is found to obtain in very different degrees; in _Tr. Weigmannii_ being very distinctly marked, and in _Tr. Kingii_ very slightly so, and in some specimens scarcely notable. It is probable, that var. B., and possibly A. also, of Mons. Bibron, may be _Pr. Kingii_; but I have not had the opportunity of ascertaining this from the actual examination of the specimens.

Found by Mr. Darwin at Port Desire, and at Santa Cruz, in Patagonia.

PROCTOTRETUS CYANOGASTER.

PLATE V.—FIG. 2.

_Squamis capitis neque imbricatis nec carinatis; temporum imbricatis,
subcarinatis, margine rotundato; aurium margine anteriore simplici;
squamis dorsalibus rhombeis, laxis, carinâ posticè acutâ; femorum
facie posteriore omninò granulosâ; corpore suprà olivaceo, fascia
utrinque longitudinali flavescenti; abdomine cœruleo._

_Proctotretus cyanogaster_, Bibr. l. c. p. 273.

Habitat, Valparaiso, and Valdivia, Chile.

DESCRIPTION.—It has been well observed by M. Bibron that this species
offers at first sight somewhat the general aspect of the genus
Algira; the acute points of the dorsal and lateral scales and the
general form giving very much that appearance.

The head is of moderate size, somewhat deflexed; the scales
moderate, flat and smooth; those of the temples are slightly
carinated, imbricated and rounded: those of the sides of the neck
small, not granular, but rhomboidal and imbricated. There is but a
single series of oblong scales between the labial ones and the
orbit. The margin of the ear is entire and simple; the scales of
the back are lozenge-shaped, the carina of moderate height but
prolonged into an acute point. Amongst those of the sides of the
neck and belly are a few which are notched at the margin.[2] The
scales of the posterior surface of the thigh are wholly granular.

Footnote 2:

This is contrary to the character given by M. Bibron, who states
that the whole of these are entire.

_Plate 6._

_Drawn from Nature by B. Waterhouse Hawkins,
on stone in Lithotint. C. Hullmandel’s Patent._
]

_1._ │_Proctotretus Kingii_ _Nat.
│Size._
_2._ │ „
───────┼───────────────────────────────
_a. b._│_Magnified View._

The proportions of the limbs vary in the two sexes. In the male
they are considerably longer than in the female. In the latter the
posterior extremity when placed against the side extends only to
the arm, in the former it reaches to the ear. The ground colour of
the back is chesnut brown or greenish brown, with a bright
metallic green glance in certain lights; there are two light buff
longitudinal fasciæ running the whole length of the body; the
under parts are of a bright metallic blue colour. Mr. Darwin
states that in one specimen there were emerald spots on the sides,
which did not exist in another individual. This may possibly be a
sexual peculiarity.

DIMENSIONS OF A MALE SPECIMEN.

DIMENSIONS OF A MALE SPECIMEN.
Inches. Lines.
Length of the head 0 6
of the body 1 9
of the tail 3 3
────────────────────────────────────────────
Total length 5 8
Length of anterior extremity 1 0
of posterior extremity 1 5

Found by Mr. Darwin at Valparaiso, and at Valdivia; the former is a very dry rocky country, with a scanty vegetation; whereas the latter is nearly level, covered with the thickest forest, and the climate exceedingly humid.

PROCTOTRETUS KINGII, N.S.

PLATE VI.—FIG. 1, 2.

_Squamis capitis neque imbricatis nec carinatis; supralabialibus in
serie unicâ; aurium margine anteriore granuloso; interdum
unidentata; squamis, dorsalibus carinatis, posticè acuminatis,
femorum facie posteriore præcipuè granulosâ, sed portione parvâ,
caudam versus, squamis parvis, rotundatis imbicratis tectâ._

Habitat, Port Desire in Patagonia.

DESCRIPTION.—General form robust and full; the head short, thick, and
passing into the neck without any distinct contraction; the muzzle
rounded. Scales of the head larger in proportion than in _Pr.
Fitzingerii_. Ear large, oval, with the anterior margin granular,
sometimes slightly toothed. Scales of the temples of moderate
size, imbricated, smooth, somewhat raised. A single range of oval
moderate-sized scales between the labial and the orbital scales on
the sides of the neck, above and behind the shoulder small,
granular, and some of them having a minute pore. Scales of the
back of moderate size, larger than in _Fitzingerii_, rhomboid,
having a rather prominent carina, and terminating in a distinct
point. Scales of the under parts smooth and rhomboidal. The
posterior surface of the thighs is for the most part granular, but
a small portion near the groin is covered with larger imbricated
scales; to a much smaller extent, however, than in _Fitzingerii_,
and other species which possess this character.

The general colour of the upper part of this species is a rich
dark brown, with whitish transverse bands and spots, having a
black margin. I have figured in fig. 2, of Plate VI., a remarkable
variety in which the bands are alternate black and white, and a
broader and a narrower longitudinal fascia of a yellowish-white
colour, run the whole length of the body on each side. The under
parts are yellowish-white, with dark or almost black spots; under
the throat bluish-gray with white spots.

DIMENSIONS.
Inches. Lines.
Length of the head 0 8
of the body 2 3
of the tail 3 4
────────────────────────────────────────────
Total length 6 5
Length of anterior extremity 1 1
of posterior extremity 1 4

This species much resembles _Pr. Fitzingerii_ in many of its characters, as well as in its size. It may, however, be at once distinguished from it by the character of the scales of the back, which in this species are very distinctly carinated, of a rather elongated form, and pointed at the extremity; whereas in the other they are shorter, smaller, the carina is very slight, almost indistinct, and the posterior extremity is obtuse.

The tail in the larger figure of our plate is deformed, having been renewed. The specimen figured at (2,) in the same plate, is so remarkably distinct in the colours and marking, as to lead me to suppose that it may possibly be a different species.

PROCTOTRETUS DARWINII.

PLATE VII.—FIG. 1, 2.

_Corpore subdepresso; capite squamis numerosis, parvis, subelevatis,
lævibus non imbricatis; aurium margine anteriore integro; temporibus
colloque granulatis; serie unicâ squamarum supralabialium; facie
posteriore femorun partìm granulosâ, partìm squamis imbricatis
tectâ._

Habitat, Bahia Blanca, Northern Patagonia. Mr. Darwin.

_Plate 7._

_From Nature by B. Waterhouse Hawkins,
in Lithotint C. Hullmandel’s Patent._
]

_1._ │_Proctotretus Darwinii. Nat. Size._
_2._ │ „
──────────┼───────────────────────────────────
_1 a & b._│_Magnified Views._
_2 a._ │ „

_Plate 8._

_B. Waterhouse Hawkins lithog._
]

_1._ │_Proctotretus Weigmannii._
_2._ │ „
─────┼──────────────────────────
_1a._│_Magnified Views._
_2a._│ „

DESCRIPTION.—The general form of this new species is similar to that
of _Pr. Weigmannii_, but less elongate and somewhat more
depressed, resembling in general appearance some of the forms of
the genus Sceloporus. Head covered with rather small and
consequently numerous scales, slightly elevated, and separated
from each other by distinct and deep lines. A single series of
small scales between the labial scales and the orbit. The exterior
margin of the ear is entire and even. Scales of the temple and at
the sides of the neck wholly granular, the latter very small. The
scales of the back are small, flat, with a very low carina, and
not pointed at the posterior extremity. There are about twenty
rows of dorsal scales. The posterior surface of the thighs is
granulated, excepting a small patch near the tail of imbricated
scales, similar to those of the inferior surface, as in _Pr.
Weigmannii_. The tail is of moderate length, and the scales which
cover it are short, depressed, and obtuse in comparison with those
of several other species. The pre-anal pores, which are peculiar
to the male, are about ten in number.

The general colour is gray, with two light longitudinal lines on
each side, and a row of black spots along the inner margin of the
dorsal ones. The under surface is nearly white, with black dots
under the throat.

The anterior legs, when stretched backwards against the side,
reach about two-thirds towards the thigh; and the posterior when
stretched forwards, extend to the shoulder.

DIMENSIONS.
Inches. Lines.
Length of the head 0 5
of the body 1 6
of the tail 3 4
──────────────────────────────────────────────
Total length 5 5
Length of anterior extremities 0 8
of posterior extremities 1 2

It is at first sight extremely difficult to distinguish this species from younger individuals of _Pr. Fitzingerii_, from which, however, it differs in the more linear form of the supralabial scales, in the absence of imbricated scales on the lateral fold of the neck, the more entire margin of the ear. In the existence of a patch of larger imbricated scales on the posterior surface of the thighs, it resembles _Pr. Weigmannii_; from which, however, it may be at once distinguished by the single row of supralabial scales, the later species having a double row.

PROCTOTRETUS WEIGMANNII.

PLATE VIII.—FIG. 1, 2.

_Capite squamis lævibus non imbricatis tecto; auribus rotundis margine
anteriore minutè granulato. Seriebus duabus squamarum
supralabialium. Femorum facie posteriore partìm granulosâ, partìm
squamis minutis imbricatis tectâ._

_Proctotretus Weigmannnii_, Bibr. l. c. p. 284.

Habitat, Northern Patagonia and La Plata.

DESCRIPTION.—Head rather short, covered with numerous slightly raised
scales, not carinated nor imbricated; snout rather obtuse and
slightly rounded, nostrils semicircular. Two series of very small
scales between the labial scales and the orbit. Ear of moderate
size, the anterior margin furnished merely with minute granular
scales. Scales of the temples flat and smooth. Fold on the sides
of the neck distinctly marked, anteriorly bifurcated; the
remainder somewhat waved. Sides of the neck granulated scales of
the whole of the upper and back parts of the body and tail of
moderate size, the carina little elevated and the point but
slightly prominent. The scales of the inferior parts of the neck
and body are smooth, polished, and imbricated, those towards the
sides of the neck minutely emarginated. The scales of the limbs
resemble those of the body; those of the upper surface being
carinated and those beneath smooth. The posterior face of the
thighs is generally covered with granular scales, but there is on
this part near the tail, a distinct patch of imbricated scales
resembling those of the inferior surface of the thighs, a
character by which this species may at once be distinguished from
all others. The anterior extremity placed against the side reaches
about two-thirds of the distance towards the groin; the posterior
extremity reaches forward to the shoulder.

COLOUR.—The back and sides are brownish gray, with a yellow
longitudinal band on each side of the back, separating transverse
black or dark brown bands of various size and form; and there is
in most on each side a smaller interrupted yellow band. The under
parts generally of a yellowish white, in some individuals sparsely
dotted with black. Mr. Darwin says of some individuals of this
species that they have “an orange-coloured gorge, and faint
stripes of blue,” also “ash-grey with dark brown marks and specks
of orange and blue.”

DIMENSIONS.
Inches. Lines.
Length of the head 0 5
of the body 1 5
of the tail 2 2
────────────────────────────────────────────
Total length 4 2
Length of anterior extremity 1 1
of posterior extremity 0 8

This species was found by Mr. Darwin at Bahia Blanca and at Rio Negro, on the northern confines of Patagonia, and at Maldonado, near the mouth of the Rio Plata.

_Plate 9._

_Drawn from Nature by B. Waterhouse Hawkins,
on stone in Lithotint C. Hullmandel’s Patent._
]

_1._ _Tropidurus_ _multimaculatus._ _Nat. Size._
_2._ _pectinatus_ „
───────────────────────────────────────────────────────────
_1a. 1b._ _Magnified Views._
_2a._ „

PROCTOTRETUS MULTIMACULATUS.

PLATE IX.—FIG. 1.

_Corpore subdepresso; capite squamis numerosis parvis tecto; auribus
parvis, margine lævi; seriebus quatuor squamarum supralabialium;
squamis temporum imbricatis; collo granuloso; femorum facie
posteriore partìm granulosâ, partìm squamis imbricatis tectâ._

_Proctotretus multimaculatus_, Bibr. l. c. p. 291.

Habitat, Bahia Blanca, Northern Patagonia.

DESCRIPTION.—The body depressed and wide—the head triangular, the
muzzle rather acute. Nostrils prominent and nearly round. Scales
of the head very small and numerous; those of the temple
rhomboidal and imbricated. There are four series of small
irregular scales between the labial and suborbitar. The sides of
the neck are wholly granular; the scales of the body very small;
those of the upper parts rhomboidal, flat with very low carina,
and obtuse at the apex—beneath they are also small and rhomboidal;
the posterior surface of the thighs is granular, but, as in some
other species, there is, near the groin, a distinct patch of
imbricated scales like those of the inferior surface. The tail is
broad to some distance from the origin, and then tapers to the
extremity. The scales of the tail are rather small, short and
obtuse.

The anterior extremity placed against the sides reaches about
two-thirds the distance towards the posterior, and the latter
reaches forwards to the shoulder.

The ground colour of this species is gray, with numerous small
black spots, some of which are bordered with white. The under
parts are white, and in one specimen in Mr. Darwin’s collection
there are on the belly numerous distinct small black spots. His
description of the colours is as follows:—“Colours above
singularly mottled. The small scales are coloured brown, white,
yellowish red and blue, all dirty, and the brown forming
symmetrical clouds. Beneath white, with regular spots of brown on
the belly.”

DIMENSIONS.
Inches. Lines.
Length of the head 0 8
of the body 1 8
of the tail 3 0
────────────────────────────────────────────
Total length 5 6
Length of anterior extremity 1 0
of posterior extremity 1 6

Found at Bahia Blanca, on the northern confines of Patagonia. The following remarks of Mr. Darwin on the habits of this species are very interesting. “In its depressed form and general appearance it partakes of some of the characters of the Geckos. Its habits are singular. It lives on the dry sand of the beach, at some distance from the vegetation, and the colour of the body much resembles that of the sand. When frightened it depresses its body, stretches out its legs, and closing its eyes tries to escape detection. If pursued it buries itself with great quickness in the sand; but as its legs are short, it cannot run very swiftly.”

PROCTOTRETUS PECTINATUS.

PLATE IX.—FIG. 2.

_Capite squamis subæqualibus, rhomboideis, imbricatis, carinatis
tecto._

_Proctotretus pectinatus_, Bibr. Hist. Rept. IV. p. 292.

Habitat, Patagonia.

DESCRIPTION.—The scales of the head are narrow, closely imbricated,
strongly but not acutely carinated, and the anterior ones arranged
in somewhat of a radiating direction from the muzzle. There is but
a single series of scales between those of the upper lip and the
orbit, and these, together with all the scales about the head,
partake of the carinated and elongated character already
described. A single strong triangular scale and two smaller ones
are placed on the anterior margin of the ear, which is narrow,
oval and reniform. The scales of the temples and sides of the neck
are rhomboidal, acute, carinated and imbricated. There is a
longitudinal fold on each side of the neck and a transverse one
anterior to the shoulder, behind which is a deep depression. The
scales of the back and side are prominently and acutely carinated,
those of the central line being rather more prominent than the
others; and above this there is on each side a marked longitudinal
lateral crest extending from beneath the eyes to the base of the
tail. The scales constituting these crests are very prominent,
narrow and acutely carinated. The scales of the belly are also
imbricated and rhomboidal, but flat; those of the under surface of
the hands and feet are carinated; and those of the toes have three
carinæ. The body is somewhat depressed as is the tail at its
commencement, becoming more rounded and rather abruptly smaller at
some distance from its origin. The fore-foot reaches to about
two-thirds of the distance from the shoulder to the side, and the
hinder extremity thus placed extends to the shoulder.

The colours of this most elegant of all the species of the genus
are very beautiful. “This is the most beautiful lizard,” says Mr.
Darwin, “I have ever seen; the back has three rows of regular
oblong marks of a rich brown, the other scales symmetrically
coloured either ash or light brown; many of them of a bright
emerald green; beneath pearly, with semilunar spots of brilliant
orange on the throat.” I find in the specimens I have examined
that the pectinated lateral crests are white, and the brown oblong
marks of the back are bordered with a similar colour. There are
always three white transverse lines across the head.

DIMENSIONS.
Inches. Lines.
Length of the head 0 7
of the body 1 7
of the tail 3 1
────────────────────────────────────────────
Total length 5 5
Length of anterior extremity 1 0
of posterior extremity 1 5

This species, as has been observed by M. Bibron, who first described it, may be at once distinguished from every other by the character of the scales of the head, which, instead of lying flat, with the edges in contact, are all of them imbricated and carinated. Another obvious distinguishing character, is the narrow line of prominent scales running the whole length of the body on each side, forming a sort of _pectinated_ lateral crest, from which circumstance it has derived its name.

Found by Mr. Darwin, at Bahia Blanca, and Port Desire in Patagonia.

GENUS—DIPLOLÆMUS. _Bell._

_Caput breve, latum, subtriangulare. Aures parvæ, ovatæ, margine lævi.
Nares magnæ, rotundæ. Collum infrà transversè, ad latera
longitudinalitèr plicatum. Corpus subdepressum, non cristatum. Cauda
teres, breviuscula, læevis. Pedes breves, robusti. Squamæ capitis
numerosæ, parvæ, rotundatæ, non imbricatæ—corporis atque caudæ suprà
minimæ, læves, convexæ, paulò imbricatæ, infrà læves, planæ. Pori
femorales et præ-anales in utroque sexu nulli. Dentes palatini
nulli._

The new genus which I have thus defined, resembles very closely, in most of its characters, the genus _Leiosaurus_ of Bibron; from which, indeed, it scarcely differs, excepting in the absence of palatine teeth, and in the form of the suborbitar plates, which in _Leiosaurus_ are all distinct, and of nearly equal size; whereas, in the present genus, three of these are united to form one plate, resembling that in _Proctotretus_, and some other _Agamidæ_. In other respects the genera are very closely allied; but the existence or non-existence of palatine teeth, is a character of so much importance, that it appeared to me,—and in this opinion I am supported by M. Bibron, who examined the specimens with me,—that they should be considered as distinct. Both the genera are natives of South America. Of _Leiosaurus Bellii_ (Bibr.) the only known specimens were presented to me by Capt. King, who obtained them during his survey, from whom also I obtained specimens of one of the species of the present genus, _D. Bibronii_.

DIPLOLÆMUS DARWINII. _Mihi._

PLATE X.

_Squamis capitis convexis; caudâ, corpore cum capite longiore._

Habitat, Port Desire, Patagonia.