1890.] HELODERMA SUSPECTUM. 153 



elbows, and no very decided swells mark the sites of the muscular 

 masses of the thigh or brachiuni. Manus and pes are both flattened 

 from above downwards and of a subcircular outline, while from each, 

 around its anterior periphery, spring the toes of this pentadactyle 

 lizard. The digits are all of nearly the same length, but in the 

 case of manus the mid-toe appears to be the longest and the poUex 

 the shortest, while in the pes the mid-toe and the next one to its 

 outer side are of about the same length, and again the hallux is the 

 shortest. Each toe is terminated by a small, sharp-pointed, decurved 

 claw, which is of a horn-colour befoi^e the moult, but which there- 

 after is seen to be a pure gUstening white. These claws are generally 

 much worn by the constant walking of these heavy reptiles over the 

 rocks of their native liaunts, and, indeed, in very old individuals the 

 toes seem to be almost clawless, both unguiil phalanx and its horny 

 sheath having been worn down to the very base. 



As will be seen by the above table of measurements, the external 

 narial apertures are, comparatively speaking, situated rather far apart ; 

 they are, too, of good size, being of a subcircular outline, with a 

 pale-coloured mucous membrane lining them within. Heloderma 

 has fairly large eyes, in which the irides are of a dark snuff-brown, 

 and the external lids, which can be closed completely, when open 

 create an aperture broadly elliptical in outline. The opening of the 

 mouth in this reptile is very capacious, and the commissures of the 

 gape are situated at some distance posterior to vertical lines let fall, 

 on either side, from the pupils of the eyes. The lower lip is rounded 

 and is overlapped by the upper lip, the margins of which are sharp ; 

 but in the case of both the tissues are quite pliable and consist of 

 nothing more than the flat scutes overlying the soft parts they cover. 



Either external ear consists in an oblique slit, situated at some 

 little distance from, but in line with, the commissure of the gape ; its 

 borders are rounded, and its lower angle is the anterior one of the two. 

 Unlike some other Lizards, the tympanum is rather deeply situated, 

 and is only brought into view by carefully opening the ear, by which 

 I mean parting its margins. In front of the entrance to this aural 

 meatus, the row of tubercles bounding it are of some considerable 

 size, while those on the posterior margin of the aperture are compara- 

 tively minute, the latter being in continuation with those found 

 beneath the throat. 



This method of the arrangement of the scales or tubercles is re- 

 peated again in the vent of this animal, where we find a broad slit- 

 like aperture transversely disposed and with a soft rounded posterior 

 border, bounded by a row of very minute tubercles ; while in front 

 the opening is more rigid in character, which is largely due to the 

 far greater size of the bounding scutes and their consequent greater 

 immobility. 



Of the Teguments. — Viewed as a whole, the external epidermic 

 armour of this reptile consists in, for the entire dorsal aspect, a 

 stuccoing of knob-like tubercles of various sizes, which, as they pass 

 to the ventral surface of the body, gradually assume the flat type of 

 scale, having different forms in different localities. These tubercles 



