20 
ZOOLOGY OF THE VOYAGE OF THE BEAGLE. 
DiPLOLiEMUS Darwinii. MUli. 
Plate X. 
Squamis capitis convexis ; caudd, corpore cum capite longiore. 
Habitat, Port Desire, Patagonia. 
Description. — Head short, almost equilaterally triangular, rising obliquely from the muzzle to the 
vertex, then flattened. Nostrils large, round, each placed in front of the supra- orbital crest, 
and in a line between it and the centre of the muzzle. The ears are small, oval, the margin 
simple, and the membrana tympani superficial. The neck is considerably contracted ; it has a 
longitudinal fold on each side formed by the confluence of two others, one of which arises from 
behind the angle of the mouth, and the other from above the ear, which is, as it were, enclosed 
between them ; they coalesce a little behind the ear. There is also a distinct transverse fold 
on the throat, very similar to that in Leiosaurus BelUL The body is moderately thick, some- 
what depressed, and without the slightest appearance of a longitudinal crest, or any elevation 
along the median line. The tail is somewhat longer than the head and body, nearly round and 
tapering almost evenly from its origin to the apex. The fore legs ai’e short and moderately 
robust, the toes short, nearly equal ; the hinder legs moderately long. The former when placed 
against the sides, do not reach the thighs by nearly a third of the distance between the two 
limbs ; the latter when directed forwards, just reach the axillae. The cloacal covering is semi- 
lunar, turgid, and the margin quite simple. 
Scales covering the upper surface of the head numerous, rounded, and considerably ele- 
vated ; those between the two supra-orbital semicircles are in a double series. The occipital 
plate is oval, raised from the margin, hollowed immediately around the centre which is again 
raised like a minute tubercle. Above the labial scales, is a series of equal, rounded, oblong 
scales, and between these and the principal suborbital is a single series of smaller ones. Scales 
of the whole of the upper and lateral parts of the neck and body extremely small, slightly 
elevated, passing at the sides into a flatter and more expanded form. Those of the whole of 
the under parts are quite flat and imbricated. Beneath the anterior parts of the lower jaw, and 
behind the broad mental scales, are a series of flat, hexagonal scales on each side, passing back- 
wards and outwards, the front pair large and oblong and the others diminishing by degrees. 
The scales of the throat are very small, those on the fold larger and acutely rhomboidal. The 
scales of the anterior part of the belly are also rhomboidal and those of the posterior portion 
hexagonal or nearly quadrate. The tail is covered by scales disposed in whorls, those on the 
median line beneath being larger than the others. Beneath each toe is a series of transverse 
hexagonal imbricated scales. 
The colours and markings of this species are very difficult to be described, on account of 
the great irregularity of their disposition. The ground colour of the head is yellow, passing 
into grey on the back part. The anterior part has several small spots of a dark brown colour, 
and there is a larger one on each orbit, another between the eye and the ear, and others on the 
back part of the head extending to the neck. The middle of the back is reddish yellow, on 
