Feb., 1912. Mammals of Illinois and Wisconsin — Cory. 451 



Family VESPERTILIONID.^:. Typical 



Bats. 



This is by far the largest famih' belonging to the order. Its mem- 

 bers are insectivorous, nocturnal and crepuscular; and are characterized 

 by having the ears separate, with a small anterior basal lobe and 

 tragi well developed. The muzzle is simple, without fleshy appendages 

 (differing in this from the so-called Leaf -nosed Bats) ; tail attached 

 to interfemoral membrane and extending to its edge or slightly be3'ond ; 

 clavicle present and well developed; radius long and curved; ulna 

 rudimentary; pollex free from and extending beyond edge of wing 

 inembrane, ending with a hooked claw; presternum with prominent 

 "keel" for the attachment of the large pectoral muscles; ribs much 

 flattened and occasionally more or less anchylosed at their margins; 

 cerebral hemispheres smooth ; placenta discoidal and deciduate ; mam- 

 mae thoracic; testes abdominal or inguinal. The milk teeth are unlike 

 the permanent teeth and are usually replaced by the latter at an un- 

 usually early period, the cranial sutures become anchylosed and often 

 disappear much earlier in life than in most of our mammals. The 

 structural character of the hair is peculiar.* 



Of the 100 or more North American species and subspecies, nine 

 species belonging to 6 genera are known to occur within our limits, and 

 it is probable that another genus and species {Corynorhinus macrotis) 

 and possibly a representative of another family {Nycti nonius dcpressus) 

 may ultimately be added to the list. 



KEY TO THE GENERA. 



GROUP 1. Upper incisors (front teeth between canines) 2. 

 Upper surface of interfemoral membrane (membrane 

 connecting tail with legs) completely furred; whole 

 number of teeth 32. Genus NYCTERIS, p. 470. 



Upper surface of interfemoral membrane entirely bare 

 or furred slightly at extreme base; whole number 

 Front view, showing up- of teeth 30. Genus NYCTICEIUS, p. 475. 



per incisors and canines 

 much enlarged. 



* For remarks concerning the structural variation in the hair of Bats, see page446. 



