MAMMALIA 451 



No wings. 



Thumbs not opposable. 



Incisors and canines small, 



Insectivora. 

 Incisors chisel-shape and canines 



wanting Rodentia. 



Canines large; other teeth often pointed, 



Carnivora. 



Thumbs opposable Primates. 



Order i . Edentata (toothless) . Placentalia in which the teeth 

 are absent or imperfect, being destitute of enamel and true roots. 

 They are found both in the Old World and in the New, especially 

 in the tropics of the southern hemisphere. The chief repre- 

 sentatives are the sloths and the hairy ant-eater of Central and 

 South America, the armadillo of South America and as far north 

 as Texas, and the scaly ant-eaters of Asia and Africa. The 

 sloths are sluggish vegetarians living in the trees, on the branches 

 of which they hang or climb, back downward, by means of their 

 long curved claws. The ant-eaters are almost wholly devoid of 

 teeth, but have narrow extensible tongues which they project 

 into ant-holes, capturing the ants by the sticky saliva. The 

 group is primitive and degenerate, and furnishes a noteworthy 

 exception to the statement that the mammals lack an external 

 skeleton. Overlapping bony scales, or plates in the form of 

 rings, may furnish a complete armor by means of which they are 

 kept from extermination in spite of their inoffensive, sluggish 

 habits. This is best seen in the armadillo. 



Order 2. Insectivora (insect-feeders). These are small mam- 

 mals with clawed digits, which feed on insects and other small 

 invertebrates. The brain is small and smooth. The incisors 

 are small. Many burrow, and have special adaptations for 

 such a life; among these one of the most interesting is the de- 

 generation of the eyes. The moles, shrews and hedgehogs are 

 the chief representatives. The moles have the reputation of 

 eating corn and other planted grains. Their burrows frequently 

 follow the rows. Their food, however, is the insects that collect 

 about the planted grain. They do much damage to turf in 

 making their burrows. A single specimen has been known to 



