ENCEPHALON OF REPTILES. 



Z91 



functions of organic life. In the active state of the summer 

 season, such mutilation is followed by death in one or two hours, 

 rarely more. 1 



In serpents, the cerebellum, fig. 188, c, expands into a depressed 

 semicircular lobe directed backward from the confluence of the 

 restiform crura and overlapping the major part of the fourth 

 ventricle, which appears as a short median fissure. The optic 

 lobes, ib. b, now expanded 188 



to the breadth of the cere- 

 bellum, show both a longi- 

 tudinal and a transverse 

 fissure, the latter crossing; 

 near the hinder border, and 

 giving to this part of the 

 brain a close resemblance 

 to its homoloa;ue the 'bige- 

 minal bodies ' in Mammals. 

 The optic lobes are hollow : 

 the cerebral crura show 

 slight enlargements, like 

 optic thalami, anterior to 

 the optic lobes, before ex- 

 panding into the hemi- 

 spheres. These are pressed 

 into close contact medially, 

 and compose a prosence- 

 phalon nearly as broad as 

 long, and double the 

 breadth and length of the 

 mesencephalon. The outer 

 surface of the hemispheres 

 is smooth, composed of a 

 thin layer of vascular or 

 grey neurine. Into their 

 cavity or ventricle a ' cor- 

 pus striatum' projects from 

 the under and outer side ; beneath or mesiad of which is a minor 

 prominence. The septum, formed by the thin mesial wall of 

 each hemisphere, is perforated for the passage of a ' choroid 

 plexus.' The ventricles are continued forward into the olfactory 

 J lobes, fig. 188, i ; each is marked off by an oblique fissure from 

 the fore part of the hemisphere, which it equals in breadth; 



HY'liiltll 

 VI 



Brain and Xcrves of the Boa Constrictor, lit, 



CCI. 

 U 2 



