OCR Text |
Show 1890.] HELODERMA SUSPECTUM. 155 state of things continues all the way to the root of the tail, scarcely any perceptible difference in the size of the individual tubercles, although perhaps the larger ones may range along the middle of the back. They are so arranged that any single tubercle in one row stands opposite the interspace between two other tubercles either in the row in front of or behind it. When the Heloderm is fat aud in good condition, the individual tubercles stand apart from each other, separated by a distance equal in any case to about the diameter of the base of the tubercle next to the space. Aud when the reptile is laying out perfectly straight and at rest, these several rows of tubercles seem to be separated from each other by crease-like lines marking the intervening skin ; but the moment the animal twists to one side or the other, these transverse lines are immediately obliterated, while oblique ones, running straight down the concaved side, take their place. As I have already described above, these knob-like tubercles of the dorsal aspect of the Heloderm's body in passing down the sides gradually assume the flat scale-like type. From between the armpits and the groins these are of an even oblong form, arranged in regular transverse rows, being in contact with each other, while the individual scales of one row break joints with the scales in front of and behind them, much in the same manner as bricks in a building do. Between the legs in front these oblong scales gradually assume a rounded form, and in passing still more anteriorly they become still smaller, to eventually merge into the minute tubercles, already described, that cover the throat. These ventral scales also become more rounded as they pass between the hinder pair of limbs, as well as slightly smaller. The two middle preanal scales are markedly larger than the few remaining ones that make up this row upon either side of them; and, as I have already said, the tubercles on the posterior margin of the vent are quite minute in comparison. The tubercles covering the dorsal aspect of the great rounded tail of this reptile pass regularly from those on its back, having the same arrangement and character, only they are placed closer together, being nearly or quite iu contact with each other. Further, as these caudal tubercles pass round to the underside of this appendage, they, too, become gradually flatter, but in their case only two middle rows running the length of the underside of the tail may said to be flat. The rows of small tubercles covering any one of the limbs are arranged much after the same fashion as are those upon the back, while upon the soles of the feet they are seen to be very much worn. Any single toe shows a transverse arrangement of its single row of oblong scutes, both upon its ventral and dorsal aspect, and between these, on either lateral surface of the digit, is another longitudinal row of rounded scales, all three being carried down so that the terminal ones surround the claw. As has already been hinted at in a foregoing paragraph, in shedding but small patches of skin come away at a time, aud these show a perfect casting of the scales or tubercles they originally covered. Of other Parts which may be examined externally.-By the aid |