I 9 8 



ANIMAL BIOLOGY 



veloped. Does this mean a low or a well-developed mam- 

 mal? Where does it have a thumb? (Fig. 361.) Does 

 the thumb have a nail ? Is the tail hairy or bare ? Why ? 

 Do you think it prefers the ground or the trees ? State 

 two reasons for your answer. It hides in a cave or bank 

 or hollow tree all day, and seeks food at night. Can it run 

 fast on the ground? It feigns death when captured, 



and watches for a 

 chance for stealthy 

 escape. 



The kangaroo 

 (Fig. 362), like the 

 opossum, gives 

 birth to imperfectly 

 developed young. 

 (Kinship with what 

 classes is thus in- 

 dicated ?) After 

 birth, the young 



(about three fourths 

 FIG. 362. GIANT KANGAROO. 



of an inch long) 



are carried in a ventral pouch and suckled for seven or 

 eight months. They begin to reach down and nibble grass 

 before leaving the pouch. Compare fore legs with hind 

 legs, front half of body with last half. Describe tail. 

 What is it used for when kangaroo is at rest? In jump- 

 ing, would it be useful for propelling and also for balanc- 

 ing the body ? Describe hind and fore feet. Order 



Why? See key, page 193. 



Imperfectly Toothed Mammals. These animals live 

 chiefly in South America (sloth, armadillo, giant ant-eater) 

 and Africa (pangolin). The sloth (Fig. 363) eats leaves. 

 Its movements are remarkably slow, and a vegetable growth 



