Order CHIROPTERA 63 



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

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

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

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

 spiders, snails, and worms, as well as on insects. 



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

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

 no more than half as large. The tail is too short to leave a 

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

 shrew is only about V± inch in diameter. 



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

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

 state. 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- 

 necticut to northeastern Colorado and southward into Mexico 

 and Florida. 



ORDER CHIROPTERA 

 Bats 



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

 sive membranous wings formed of thin skin that extends from 

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

 spicuously long bones of their forearms and ringers down to 

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

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

 twilight of evening or of early morning. They are extremely 

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

 adept at avoiding obstacles and successful in catching insects on 

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

 unique sonar system. They emit from their throats squeaks 

 and supersonic vibrations, inaudible to man, and perceive and 

 localize the reflected sound waves or echoes through highly 

 developed mechanisms of their ears. 



Hats are distributed over the whole world and are of many 

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

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

 shaves the skin of Large mammals (occasionally man) and laps 

 up the blood as food. The largest bats are the fruit bat^ or 

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



