When frequently handling the young constrictors, one has been able to _feel_ as well as to observe the action of the ribs. As they pass through the hand, you feel them expanded, so as to present a flatter under surface. In _Ptyas_ the back is remarkably keeled when crawling, a section of his body presenting the form of the middle diagram given below. [Illustration] Schlegel describes the forms which the bodies of various snakes assume in swimming, climbing, clinging, etc. Sometimes they are laterally compressed, at others flattened. The three figures above are on a much reduced scale, but give an idea of the sections of three different snakes, though each snake is capable of several such changes of form. When snakes climb against the glass of their cages, you may easily discern the flattening of their bodies. In this action there seems to be a compressing power, any hold of the scutæ against a polished plane being, of course, impossible; yet without holding they seem to cling; and the ribs advance in wave-like intervals just the same, with an intermediate space at rest until in turn the wave is there and passes on, while from an anterior portion another wave approaches, and so on. Yet the _compressure_ strikes one forcibly. There is also the evident support of the tail in a large python thus crawling to the very top of his cage. Mr. Gosse observed the dilatation and flattening of the body in the climbing snakes, and that they had no more difficulty in gliding up a tree or a wall in a straight line than on the ground. In the _Anecdotes of Serpents_, revised for the Messrs. W. & R. Chambers, of Edinburgh, in 1875, from the tract by the late John Keast Lord, I also recorded my observations on this peculiarity. Some young Jamaica boas crawled to the top of their cage as soon as they were born. I saw them the same day; _held_ them, as well as it was possible to hold threads of quicksilver; _felt_ them, too, for the exceedingly juvenile constrictors tied up my fingers cleverly. So did some young boa constrictors, born alive at the Gardens, June 30, 1877. They were from fifteen to twenty inches in length, and had teeth sufficiently developed to draw blood from Holland’s hand, showing fight and ingratitude at the same time. They were exceedingly active, and fed on young mice, which they constricted instinctively. One of them, known as ‘Totsey,’ subsequently _hung_ for her portrait, as on p. 201.