MAMMALS 261 



silky; zygomatic arch of i^kull wanting: many species, which are found 

 throughout the world, except in the Australian and South American 

 regions; about 36 species and 6 genera in the United States. The 

 shrews are among the smallest mammals. They live in shallow tunnels, 

 in run-ways in moss and mold and under logs and brush, feeding on 

 worms, grubs, snails, mice and other small animals, including one 

 another, and are noted for their fierceness and voracity. They raise 

 two or more litters of 6 to 10 each during the summer and fall, and do 

 not hibernate. 



Key to the United States Genera of Soricidae 



ai Tail long, being much longer than the head (Fig. 146). 



bi Body 100 mm. to 130 mm. long i. Sorex. 



bo Body about 1 50 mm. long 2. Ncosorex. 



bs Body about 85 mm. long 3. Microsorcx. 



ao Tail short, being usually shorter than the head (Fig. 147). 



bi Teeth 32; size large 4. Blarina. 



bo Teeth 30; size small 5. Cryptotis. 



bs Teeth 28; size small 6. Notiosorex. 



I. Sorex L. Long-tailed shrews. External ears well developed, 

 generally appearing above the fur and directed backwards; tail about as 

 long as the body; dentition 4/2, i /o, 2/1,3/3: about 40 North American 

 species, 22 in the United States. 



i^ff^ 



a h 



Fig. 145. — Upper jaw of Sorex personaliis: a, lateral view; h, lower surface {from Merriam) . 



S. personatus Geoffroy. Common shrew (Fig. 145). Body brown 

 above, gray beneath; length 100 mm.; tail 38 mm.; hind foot 12 mm.: 

 New England to Alaska; southward to southern Pennsylvania, Tennessee 

 and northern Nebraska, and in the higher Alleghenies into North 

 CaroHna; not in the southern Rockies and the Cascade-Sierra systems; 

 Boreal and Transition zones; the commonest species. 



S. fontinalis Hollister. Like 5. personatus, but with a much shorter 

 tail: District of Columbia and its neighborhood. 



5. dispar Batchelder. Size large; body stout, slate-color; length 

 130 mm.; tail 60 mm.; hind foot 15 mm.: Adirondack and Catskill 

 Mountains; West Virginia, j 



