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Show J 50 DR. R. Vi. SHUFELDT ON [Apr- Ij day suns, and I have satisfied myself that upon these and other occasions, when I have closely watched them, they possess to a certain extent chameleonic powers, for I have observed the orange part of their scaly armour pass from that colour to a decided salmon tint and vice versa, remaining normally, however, at some shade of orange or yellow. When thus sunning themselves they have a habit of stretching their limbs backwards, even to the extent of having the feet with their dorsal aspects in contact with the ground, the palms and soles being directed upwards. They will then close their eyes and lay in this position for hours at a time. So far as their physical strength is concerned, it seems to be about equal to that of young Alligators of a corresponding size ; they do not, however, possess the power of striking a blow with the tail, enjoyed by the latter reptile. And in getting over rough ground, where branches, large stones, or other obstacles stand in the way, Heloderms evince no little patience, ingenuity, and downright obstinacy in overcoming such barriers to their progress. By a series of simple experiments I have been enabled to satisfy myself that the senses of sight, smell, and hearing are all quite acute in these reptiles, and they are also sensitive to the sense of touch. As to their general intelligence, however, or such mental attributes as they may be possessed of, I have made no special investigations, but from my casual observations I am inclined to believe that they stand rather above the average reptile in both of these respects. II. ON THE FORM AND EXTERNAL CHARACTERS OF HELODERMA SUSPECTUM. One of these reptiles in m y possession is considerably larger than the other, and by an approximate estimate only of their respective lengths, for I intend to present exact measurements further on, I would say that the smaller of the two was, from tip to tip, about 28 centimetres long, while the other has a total length of about 41 centimetres. The smaller one is by far, both in its markings and general coloration, the handsomer of the two. M y large Heloderma has a total length of 41*3 centimetres and a mid-girth of 18 centimetres, but this latter, of course, is very variable, as the animal may alter it considerably by inspiration and expiration at its will. Other measurements, which I have carefully taken, are presented in the accompanying table, and they will give a fair idea of the proportions of one of these reptiles. It will be seen also that the relative proportions vary with age. Moreover, as with all Vertebrates, these proportions may actually vary for each individual, just as we find robust and stout men to compare with slender and tall men. Table of Measurements. (Measurements in centimetres and fractions.) Larger one. Smaller one. Total length 41-3 29*2 Mid-girth (variable) 18*0 12*1 |