" I now proceed to the first of the two points above alluded to, and have to state my opinion that the Boa Constrictor does respire 'when his head and neck have no other appearance than that of a serpent's skin stuffed almost to bursting ;' and I think that, upon a more close examination, the same phenomenon would have been observable in the serpent shipped at Batavia. It is to be regretted that the dissec tion of that serpent appears to have been confined to the stomach ; at least nothing is said of any other part of the animal. I have never had an opportunity of dissecting the pulmonary system of a boa, or of satisfying myself as to the structure of the extremely long trachea, which must be very firm to resist such an immense pressure ; but I believe, from a near and accurate inspection, in company with others, that respiration goes on during the period of the greatest dilatation. While these serpents are in the act of constringing or swallowing their prey, they appear to be so entirely pervaded by the Upflts [appetite] which then governs them, that I am convinced they would suffer them selves to be cut in pieces before they would relinquish their victim.
I have assisted in taking them up, and removing them with their prey in their coils, without their appearing to be in the least disturbed by the motion, excepting that, if after the victim is no more and the constric tion is somewhat relaxed, an artificial motion be given to the dead body, they instantly renew the constriction. When thus employed they may be approached closely and with perfect security for the reason above stated, and I have uniformly found that the larynxes, during the operation of swallowing, protruded sometimes as much as a quarter of an inch beyond the edge of the dilated lower jaw. I have seen, in company with others, the valves of the glottis open and shut, and the dead rabbit's fur immediately before the aperture stirred, apparently by the serpent's breath, when his jaws and throat were stuffed and stretched to excess. In the case above mentioned, where the prey was taken very awkwardly, and the dilatation was consequently much greater than usual, I saw this wonderful adapta tion of means to the exigencies of the animal much more clearly than I had ever seen it before.
" With regard to the next point, it is more difficult to account for the variance between the agony of antipathy shown by the goat as described by Mr. M'Leod, and the indifference which I have uniformly observed in the full grown fowls and rabbits presented to these serpents for prey. Immediately after our boa had swallowed his first rabbit, a second was introduced; but the serpent now exhibited a very different appearance. The left side of his lower jaw was hardly in its place, and he moved about the cage instead of lying in wait as on the former occasion. As for the rabbit, after ho had been incarce rated a little while, he treated the snake with the utmost contempt, biting it when in his way, and moving it aside with his head. The
snake, not having his tackle in order, for his jaw was not yet quite right, appeared anxious to avoid the rabbit, which at last stumbled upon the snake's head in his walks, and began to treat it so roughly, that the rabbit was withdrawn for fear of his injuring the snake. This treatment of the snake by the rabbit did not appear to be the effect of anger or hatred, but to be adopted merely as a mode of removing something, which he did not appear to understand, out of his way. I have seen many rabbits and fowls presented to different specimens of boa for prey, and I never saw the least symptom of uneasiness either in the birds or quadrupeds. They appear at first to take no notice of the serpent, large as it as, and when they do discover it they do not start, but seem to treat it with the greatest indifference.
I remember one evening going up into the room where one of these snakes was kept at, Exeter 'Change, and seeing the hen which was destined for the prey of the boa, very comfortably at roost upon the serpent. The keeper took the hen in his hands and held it opposite to the head of the snake, without succeeding in inducing him to take the bird, which, when let out of the keeper's hands again, settled herself down upon the serpent for the night.
" The only solution which I can offer of the difference between Mr. 31"Leod's description and my experience, in one which i do not ' propose as absolutely satisfactory, but which may nevertheless be found to approach the truth. The goats put on board at Batavia for the serpent, which it appears was brought from Borneo, were in all probability native, of Java, and if Plo, they would, according to the wonderful instinct which nature has implanted in animals for their preservation, be likely to have a violent antipathy to large serpents, such as those which there lurk for their prey. The great Python is a native of Java, and if these goats were wild, or originally from the wild stock of the island, their instinctive horror at the sight of the destroyer may be thus accounted for. But our domestic fowls and rabbits (the stock of the latter most probably indigenous, and that of the former of such remote importation, and so much changed by descent, as to be almost on the same footing), having no such natnral enemy as a large serpent, against which it is necessary for them to be on their guard, are entirely without this instinct, although it is strong enough in the case of their ordinary enemies, such as hawks, dogs, and eats ; and they consequently view the boa which is about to dash at them with the same indifference as if he were a log of wood." We now proceed to give an account of the genera and species of the family Bolder, and in doing this we shall follow the arrangement of Dr. J. E. Gray in the Catalogue of the specimens of Snakes in the British Museum.