We give his introductory words, not only because the ‘discovery’ was a great event in the history of ophiology, but as showing that to see and examine a foreign snake was at that time a rare if not a novel occurrence. He tells us that on a former occasion in 1804, he had described the anterior ribs of a cobra, those which form the ‘hood.’ At that time he was ‘not in possession of the bodies of snakes,’ so that he could compare their structure, but had _since_ found out a good deal more about their anatomy, and then he proceeds: ‘A Coluber of unusual size lately brought to London to be exhibited, was shown to Sir Joseph Banks. The animal was lively and moved along the carpet briskly; while it was doing so, Sir Joseph thought he saw the ribs come forward in succession, like the feet of a caterpillar. This remark he immediately communicated to me, and gave me an opportunity of seeing the snake and making my own observations. The fact was already established, and I could feel the ribs with my fingers as they were brought forward. I placed my hand under the snake, and the ribs were felt distinctly upon the palm as the animal passed over it. This becomes the more interesting discovery as it constitutes a new species of progressive motion, and one widely different from those already known.’ The ‘unusually large Coluber’ was probably a python. Had a previous opportunity presented itself to this scientific and thoughtful observer, Sir Joseph Banks might not have been the one to carry off the palm in this discovery. Home had already described the peculiarity of the cobra’s anterior ribs (chap. xviii.), and, as already suggested, it is scarcely possible to watch one of those larger constrictors _without_ perceiving the mode of progression. We shall see in the course of this book that snake observers have arrived at the same conclusions on several points, while wholly ignorant of what others had said or decided regarding the same. In the previous chapter the number of vertebræ forming the spinal column of three or four snakes was given, but this number varies greatly, not only in snakes but in species. In some species there are above 400 vertebræ or joints in a snake’s spine. But here is a puzzle that baffles the student. ‘Every one knows,’ says Schlegel, ‘that their number differs’ (speaking of the vertebræ), ‘not only according to the species, but also in individuals, so that sometimes we find in serpents of the same species a difference of thirty or forty vertebræ more or less.’[68] Taking this literally according to the text, one might expect to find one ring-snake in a family of ten measuring two feet, while his brother measured two yards, and a third four feet, and so on, as if each had a different number of vertebræ.