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Show 152 DR. R. W. SHUFELDT ON [Apr. 1, These bands are unbroken in m y smaller specimen, but in the larger one a single imperfect row of orange tubercles passes round the middles of the mid black bands, which are double on the black band next the body, while two or three scattered black tubercles are seen upon the intermediate orange bands. From rather above the knees and elbows down to the tips of the several digits all four of the limbs in m y smaller specimen are of a uniform shiny jetty black, which is not the case in the larger individual, where these parts are irregularly marked all over by both black and orange At present I am unable to state whether or not these markings change at all with the growth of the animal, but I am rather disposed to think that they do not. Moreover, I have had Heloderms under my observation for two years at a time, and during that period never knew the animal to shed its skin, as do some other lizards and snakes. When I say this, I do not mean to imply that a shedding never takes place, because that would not be true, for at the present time (March 7th, 1888) the skin is shedding from the toes and soles of the feet of m y larger Heloderm, leaving the scales bright and new as it comes away. What I do mean is that I have never observed it peel off in great pieces, as it is known to do in some of our Lacertilians, where I have frequently seen it slip off nearly entire, forming a tissue paper-like cast of the entire form of the lizard. Of the Form.-For the first few years of its life, the Heloderm has a broad oval outline to its head, but as the animal matures this is superseded by the marked triangular form, where the angles at the muzzle and opposite the mandibular articulations are rounded off, and we may add that at all ages the head of this lizard is always much depressed, being quite flat on top, while considerable fulness pertains to the throat posterior to the mandibular symphysis. When the animal is asleep we may by close observation see his sides swell and collapse very slightly as he breathes, and at such times, too, the most lax and posterior part of this throat-region perceptibly pulsates in synchronism with the animal's respiration. Sometimes he has a way of taking several quick breaths in rapid succession, when all these movements become much more obvious. The body of this lizard is of an elongated ellipsoidal form, being depressed, so that on section at about its middle it would show an ellipse with its major axis horizontally disposed. The tail is large and heavy, being subcorneal in form, gradually tapering to a pointed tip ; the posterior limbs spring from points at its junction with the body, and as the latter is considerably broader just beyond this point.it always gives the casual observer the impression that these hind limbs arise from the sides of the tail. No such deception ever strikes one upon viewing the anterior pair of limbs, as in that region the neck is proportionally of considerably larger calibre than is the root of the caudal appendage. There is but very little difference either in the bigness or the length of any of the limbs', though it may be slightly in favour of the hinder pair, while for their entire lengths they are much of the same calibre, showing only slight constrictions therein at the knees and |
