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Show 1890.] HELODERMA SUSPECTUM. 153 elbows, and no very decided swells mark the sites of the muscular masses of the thigh or brachium. 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 pollex the shortest, while in the pes the mid-toe and the next one to its outer side are of about the same length, and agaiu the hallux is the shortest. Each toe is terminated by a small, sharp-pointed, decurved claw, which is of a horn-colour before the moult, but which thereafter is seen to be a pure glistening white. These claws are generally much worn by the constant walking of these heavy reptiles over the rocks of their native haunts, and, indeed, in very old individuals the toes seem to be almost flawless, both ungual 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 uarial 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 iu 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 iu 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. Iu front of the entrance to this aural meatus, the row of tubercles boundiug it are of some considerable size, while those on the posterior margin of the aperture are comparatively minute, the latter being in continuation with those found beneath the throat. This method of the arrangement of the scales or tubercles is repeated again in the vent of this animal, where we find a broad slitlike aperture transversely disposed and with a soft rouuded 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 |