214 ANIMAL BIOLOGY 



has done in the case of the higher mammals. The opossum 

 family is represented by several species confined to North 

 and South America. The common Virginia opossum is 

 prized in certain localities for food. Its habit of feigning 

 death, or " playing possum," when captured or cornered 

 doubtless often serves it a good turn by deceiving its 

 enemies. The young after leaving the maternal pouch 

 are carried about on the back of the mother, re- 

 taining their hold not only by their claws, but by winding 

 their tails around the tail or limbs of their parents. 



PIG. 166. Virginia opossums. (Prom Baker.) 



The remaining orders of the Mammalia are often termed 

 the placental mammals, because the young are retained in 

 the uterus until a comparatively late stage of development, 

 being attached to the uterine wall by a vascular organ, 

 the placenta, which serves to convey nourishment and 

 oxygen to the embryo and to carry away its waste matter 

 into the circulation of the mother. 



Among the lowest of these orders are the Edentata, 

 which include the sloths, armadillos, and the ordinary 

 ant eaters. The teeth are either absent, as the name of the 

 order implies, or else very poorly developed. The sloths 

 are inhabitants of Central and South America where they 



