356 ZOOLOGY. 



is no striated body. Olfactory globules of considerable size are 

 situated at the origin of the first pair of nerves. The optic 

 lobes are in general large, situated behind, and on the same 

 plane as the hemispheres ; but the little brain (cerebellum) is 

 small, and it sends no prolongations across the medulla, so as 



Fig. 356. Pterodactyle ; a fossil or extinct animal.* 



to form a sort of ring, as in mammals. The spinal marrow, 

 compared to the brain, is large ; so also the nerves, as com- 

 pared to the cerebro-spinal axis, are larger than in the superior 

 classes of animals. 



462. The tactile sensibility is but little de- 

 veloped, the skin being generally protected by 

 horny scales ; what we call tortoisesheli is merely 

 the horny plates covering the carapace of the turtle 

 (Fig. 352), the testudo caretta. The epidermis is 

 frequently renewed, falling sometimes in portions or 

 plates, and sometimes cast off entire, as in serpents. 

 Fig 357 Serpents throw off the epidermic covering several 



' times a year. 



There is but little remarkable in the eyes of reptiles, but 

 upon the whole they resemble the eyes of birds; &pecten 



* The black part indicates the presumed contour of the skin. 



