. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. REPTiLIA. 311 hemisphere, and projecting considerably into the lateral ventricle. The furrow which se- parates the bigeminal bodies is not so deep in the Saurians as in the Chelonian order. The cerebellum is very small, being repre- sented by a transverse layer of nervous sub- stance. In the Ophidian reptiles the two hemispheres form together a mass which is broader than it is long ; the olfactory bulb is frequently of very large size, as, for example, in the Python (fig. 225); the corpus striatum is much smaller than in
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. REPTiLIA. 311 hemisphere, and projecting considerably into the lateral ventricle. The furrow which se- parates the bigeminal bodies is not so deep in the Saurians as in the Chelonian order. The cerebellum is very small, being repre- sented by a transverse layer of nervous sub- stance. In the Ophidian reptiles the two hemispheres form together a mass which is broader than it is long ; the olfactory bulb is frequently of very large size, as, for example, in the Python (fig. 225); the corpus striatum is much smaller than in the Saurians. In the Python it is divided. The bigeminal tubercles are almost globular in many species, and much smaller than the hemispheres behind which they are situated. In the Python they are remarkable, inasmuch that they are four in number, and closely resemble the corpora quadrigemina of mammalia. The cerebellum of serpents (fig. 225, c.) is exceedingly small and flattened ; it has the shape either of the segment of a circle or of a thin quadrilateral lamina, which partially covers the fourth ventricle. In reptiles, as in birds, the medulla spinalis is permeated by a canal, which is lined inter- nally with grey substance. In the Saurian and Ophidian reptiles this canal extends as far as the first coccygeal, but in the Chelonians it is shorter. The origin of the nerves derived from the enccphalon and spinal chord closely resembles what is met with in the higher vertebrata: their general distribution will be best under- stood by referring to the explanations ap- pended to the annexed figures, copied from Mr. Swan's elaborate work on the Compara- tive Anatomy of the Nervous System. Fig. Nerves of Boa Constrictor. (After Swan.) 1, ganglion of the sympathetic nerve, situated near to, and connected with, the trunk of the par vagum. 2, a branch of the sympathetic nerve passing some way in a canal at the base of the cranium, and forming a small ganglion with a branch of
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