_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.