MAMMALS. Ill 



In the four orders Edentates, Rodents, Insect! vores, and 

 Bats the surface of the cerebrum is smooth; in all the re- 

 maining orders it is at least fissured, and in most it is con- 

 voluted (see Fig. 37), this increase in surface reaching its 

 greatest development in man. Since this line of division 

 corresponds in a way with the intelligence of the forms, 

 the four orders already mentioned are grouped together as 

 Ineducabilia; the others are associated as Educabilia. 



ORDER V. CETE (Whales). 



The whales have a fish-like body, the resemblance being 

 frequently heightened by the development of a dorsal fin ; 

 and yet in all points of structure they are mammals. The 

 anterior limbs contain the same bones (except that the 

 number of joints in the fingers may be increased) as do our 



FIG. 45. Pigmy whale (Kogia floweri). From Gill. 



own, but the whole has been modified into a " flipper" for 

 use in swimming. The hind limbs are absent externally, 

 but imbedded in the flesh on either side is a bone, variously 

 interpreted as a part of the pelvis or as the bone of the 

 thigh. The body terminates in a bilobed caudal fin 

 ("flukes"), but this, instead of being vertical, as in the 

 fish, is horizontal. All of the whales have teeth in the 

 young stages ; some retain them through life, while others 

 lose them long before maturity, sometimes even before 

 birth. The stomach is remarkable for having several 

 (4-7) chambers, this complication recalling the condition 

 in the cow. 



