2 4 2 



ELEMENTAR Y ANA TO MY. 



[LESS. 



so that the whole creature becomes enclosed at will within 

 its dense and strong exo-skeleton. 



FIG. 207. DORSAL SURFACE OF THE CARAPACE OF A FRESH-WATER TORTOISE 

 (Emys). 



i8, expanded neural spines : r l r 8 , expanded ribs ; nn, first median (or nuchal) 

 plate ; py, last median (or pygal) plate ; ;#, marginal scutes. The dark lines 

 indicate the limits of the plates of the horny epidermal tortoise-shell , the thin 

 sutures indicate the lines of junction of the bony scutes. 



9. In the fact that the surface of the body has a soft in- 

 vestment which is but very partially provided even with HAIR, 



TC 



FIG 208. DIAGRAM OF A VERTICAL SECTION OF BOTH CARAPACE AND 

 PLASTRON OF A TORTOISE, MADE TRANSVERSELY TO THE LONG AXIS OF 

 THE SKELETON. 



c, vertebral centrum ; ns, neural spine which expands above into a median dorsal 

 scute ; r, rib which forms one mass with a lateral scute and terminates at a 

 marginal plate ; ic, inter-clavicular scute ; hy, hyo-sternal scute. 



man occupies a most exceptional position amongst Mammals. 

 Indeed, a copious supply of hair or feathers or scales is a 



