CHAP. IX.] 



AND OF BIRDS. 



129 



The Olfactory Lobes have, throughout the class of 

 Keptiles, a smaller proportionate size than in Fishes. In 

 Serpents (fig. 58) and Crocodiles they 

 are situated, as in some of the last-named 

 creatures, at a distance from the cerebral 

 lobes being connected with them by 

 long peduncles. In Lizards and their 

 allies the olfactory lobes are more or 

 less continuous with the cerebral lobes 

 (fig. 59) ; while in the Turtle and other 

 Chelonians, they are marked off from 

 the anterior extremities of the cerebral 

 hemispheres only by a slight constriction 

 (fig. 61, A), and each olfactory lobe is 

 penetrated by a prolongation from the 

 corresponding cerebral ' ventricle.' 



With regard to the Cranial Nerves 

 of Reptiles, it may be remarked that the 

 Trigeminus and the Vagus (or visceral 

 nerve) are still very large, but neither of 

 them swell at their roots into such dis- 

 tinct ganglia as in Fishes. The Glosso- 

 pharyngeal, or nerve of taste, joins the 

 internal nucleus of the Vagus in Amphi- 

 bia, though in Serpents and higher Rep- 

 tiles it has a nucleus of its own, distinct 

 from that of the latter. The Auditory 

 nerves are large, and in Turtles, Croco- 

 diles, and their allies, they swell into 

 distinct ganglionic enlargements at the 

 back of the medulla, on each side of the > P tic ganglion ; E) ce - 



. rebellum ; G, ganglion at 



floor Of the ' fourth Ventricle. root of vagus nerve; j, 



The brain of Reptiles, like that of P inealbod y- 

 Fishes, is still characterized by the arrangement of its 



FIG. 61. Bruin of Tur- 

 tle, side view. (Solly.) 



A, Olfactory ganglion ; 



B, cerebral hemisphere ; 



