PHYSIOLOGICAL SERIES. 



The cerebellum is of moderate dimensions and has the 

 plate-like form usual among Reptiles. It is concave in 

 front and arches forward slightly over the optic lobes. The 

 medulla shows well the characteristic Reptilian flexure. Its 

 fourth ventricle (rhomboid fossa) is considerably restricted. 



OPHIDIA. 



D. 128. A Hinged Snake (Tropidonotus natrix), shortly before 

 hatching, with the brain exposed from above, showing in 

 linear succession the olfactory bulbs, cerebral hemispheres, 

 optic lobes, and medulla. The thalainencephalon and cere- 

 bellum are respectively covered by the caudal poles of the 

 hemispheres and the hinder part of the optic lobes. The 

 epiphysis forms a minute protuberance between the cere- 

 brum and optic lobes. 



Preserved in Goadby solution. 



Rathke, Entwicklungsgesch. der Natter (Coluber natrix), 

 1839, pp. 36, 80, 130, 199. 



D. 129. A similar specimen with the brain exposed from below. 

 Preserved in Goadby solution. 



D. 130. A similar specimen with the left side of the brain laid 

 bare. The flexure of the medulla oblongata is very marked. 

 The relation between the form of the cerebral hemisphere 

 and the developing globe of the eye is well shown. 

 Preserved in Goadby solution. 



D. 131. The brain of a Python (Pytkonuba). The brain is very 

 long and narrow and peculiarly flat from above downwards. 

 (In this specimen a certain amount of this flatness is due to 

 ticial pressure during preservation*) The hemispheres 

 pear-shaped, moderately broad behind with well marked 

 caudal (pseudo-occipital) and ventral (pseudo-temporal) 

 lobes, and terminate in front in olfactory bulbs, each of 

 which i >( -rives a stout bundle of nerves. Posteriorly they 

 abut against the optic lobes. The cerebellum is poorly 

 develojc(l and forms a flat, almost horizontal, sheet of 

 IHTVOHS tissue overlying the fore part of the fourth ventricle. 



