20 ZOOLOGY OF THE VOYAGE OF THE BEAGLE. 



DiploljEmus Darwinii. Mihi. 



Plate X. 



Squamis capitis convexis ; cauda, 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 Bellii. 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 are 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 



