XII. On the structure and development the skull in the common snake (tropidonotus natrix)

The most important work on the development of this type appeared as long ago as 1839. It was by the late Professor H. Rathke, 'Entwickelungsgeschichte der Natter (Coluber natrix).’ Konigsb., 4to. From time to time during the last twelve years I have worked at the Snake’s skull, my guide being Professor Huxley’s translation of so much of Rathke’s work as bears especially upon my line of research; this I have had at hand, both in the 4 'Croonian Lecture’ and in the ‘Elements of Comparative Anatomy.’ My earliest studies of the embryonic conditions of the Snake’s skull were made on half-grown embryos of the Python (Python Sebæ), and of the Anaconda (Eunectes murinus); these were the gift of my friends Dr. Edwards Crisp, F. Z. S., and Dr. P. L. Sclater, F. R. S. Meantime I have been acquiring younger and still younger specimens of the Common Snake, but only lately have I succeeded in obtaining any embryos sufficiently immature for my first and second stages. During the last winter (February, 1877) these earlier stages happily came to hand. At the instance of Mr. P. H . Carpenter, M. Braun, of Wurzburg, sent me a considerable number of reptilian embryos in very early stages, from Professor Semper’s laboratory. These included, besides the longed-for specimens of the Common Snake, others of the Blind Worm (Anguis fragilis), the Nimble Lizard (Lacerta agilis), and the Gecko (Platydactylus). These other three types I intend to work out in due time. The Snake has the simplest skull of all; and yet, simple as it is, it is a key to that of any member of that great bundle of Vertebrate life which, including the reptiles and birds, is termed “Sauropsida.” (See Huxley, “On the Classification of Birds,” Proc. Zool. Soc., April 11th, 1867, pp. 415-472.)