>der CHIROPTERA 63 



ind hind legs as it came to these structures. The captive animal 

 Limbered slowly about the hand of its human captor, occasion- 

 illy trying to bite, but it was never successful in breaking the 

 kin. In its natural habitat, this shrew probably preys on 

 piders, snails, and worms, as nell as on insects. 



Signs. — Tracks of the least or old-field shrew are similar in 

 nost respects to those of the short-tailed shrew, but they are 

 lo more than half as large. The tail is too short to leave a 

 Irag mark in soft snow. In snow or soil, the burrow of this 

 hrew is only about -yi inch in diameter. 



Distribution. — The least shrew is probably state-wide in oc- 

 urrence, but it seems to be rare in the northern quarter of the 

 tate. Two subspecies occur in Illinois, Cryptotis parva parva 

 Say) occupying the northern two-thirds and C. p. harlani 

 Duvernoy) the southern third. The species ranges from Con- 

 lecticut to northeastern Colorado and southward into Mexico 

 nd Florida, 



ORDER CHIROPTERA 

 Bats 



Bats are the only mammals that truly fly. They have expan- 

 ive membranous wings formed of thin skin that extends from 

 he sides of their bodies out over frames composed of the con- 

 picuously long bones of their forearms and fingers down to 

 heir hind legs, fig. 39; in many species, this thin skin encom- 

 asses the tails also. Usually bats fly only at night or in the 

 wilight of evening or of early morning. They are extremely 

 gile in flight and, although they have poor eyesight, they are 

 dept at avoiding obstacles and successful in catching insects on 

 he wing. They guide themselves in the dark by means of a 

 nique sonar system. They emit from their throats squeaks 

 nd supersonic vibrations, inaudible to man, and perceive and 

 ocalize the reflected sound waves or echoes through highly 

 eveloped mechanisms of their ears. 



Bats are distributed over the whole w^orld and are of many 

 pecies. One famous bat is the vampire, which is of medium 

 ize and is found in the American tropics. It punctures or 

 haves the skin of large mammals (occasionally man) and laps 

 ip the blood as food. The largest bats are the fruit bats or 

 lying foxes of the South Pacific tropics, some attaining a body 



