_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._
[Illustration:
_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._
[Illustration:
_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.