CLASS MAMMALIA 649 



the banded ant-eaters (Myrmecobiid^:), (2) the pouched mice, 

 dasyures, andTasmanian devil (Dasyurid^e), (3) the thylacines 

 and sparassodonts (Thylacynid^e), (4) the bandicoots (Pera- 

 melid^e), (5) the pouched moles (Notoryctid,e), (6) the pha- 

 langers (Phalangerid^e), and (7) the wombats (Phasco- 

 lomyid^e). 



Order Insectivora. — Insectivores. — These are small mam- 

 mals covered with fur. They are considered the most primitive 

 of the mammals that nourish their young before birth by means 

 of a placenta. Insectivores are entirely absent from the 

 Australian region and most of South America. They are 

 nocturnal in habit and feed principally on insects which they 

 seize with their projecting front teeth and cut into pieces with the 

 sharp-pointed cusps on their hind teeth. Most of them are 

 terrestrial, but a number are subterrestrial (i.e. burrow) ; a few 

 are aquatic, and some are arboreal. 



The two families of insectivores represented in North America 

 are the Talpid^e, containing the moles and shrew moles, and 

 the Soricid^e, or shrews. The moles are stout, with short fore 

 legs, fore feet adapted for digging, rudimentary eyes, and with- 

 out external ears. The common mole, Scalops aquaticus, 

 ranges from southern Canada to Florida. It burrows just be- 

 neath the surface of the ground, and is of considerable benefit 

 because of the insects it destroys, though its upheaved tunnels 

 soon disfigure a lawn. The rate of progress underground is 

 astonishing. One will tunnel a foot in three minutes, and a 

 single specimen under normal conditions is known to have made 

 a runway sixty-eight feet long in a period of twenty-five hours. 

 (Hornaday.) 



The shrews (Soricid.e) have pointed heads, rat-like feet, 

 small eyes, a distinct neck, and small external ears. About 

 thirty- five species occur in North America north of Mexico; 

 some of them are among the smallest of all mammals. They 

 live in burrows or on the surface of the ground. The common 

 or long- tailed shrew, Sorex personatus (Fig. 516), inhabits the 



