SURVEY OF VERTEBRATES 



129 



to Men — is an expression of their success which elsewhere in the 

 animal world is not reached even by the Insects. But it makes 

 their classification a difficult problem. However, for our purpose 

 the Placental Mammals may conveniently be grouped in four 

 great legions, chiefly on the basis of the structure and function 

 of their limbs and teeth. 



The first is the immense assemblage of clawed mammals, or 

 Unguiculates. This is represented by the Insectivora, or 



Fig. 90. — Sulfur-bottom Whale, Sibbaldus sulfurous, and African Elephant, 

 Loxodonta africana, drawn to scale. (Modified, after Lull.) 



insect-eating mammals — such as Gymnura, the Hedgehogs, and 

 Moles (Figs. 201, 205); the Edentates, or toothless mammals — 

 Sloths, Anteaters, and Armadillos (Figs. 89, 204); the Chirop- 

 tera, or flying mammals — the Bats (Figs. 207, 227) ; the Ro- 

 dentia, or gnawing mammals — Squirrels, Rabbits, Guinea-pigs, 



TlfB 



Fig. 91. — Florida Manatee, Manatus americanus. 



Rats, Mice, Porcupines, and Beavers (Figs. 108, 187) ; and finally 

 the Carnivora, or beasts of prey — Cats, Dogs, Bears, Seals, 

 etc. (Fig. 104.) 



Another legion includes the completely aquatic Cetaceans — 

 Whales, Porpoises, and Dolphins. (Figs. 90, 206, 227.) 



The hoofed mammals, or Ungulates, form a great legion of 

 herbivorous animals: important subdivisions being the Artio- 



