138 WALTER LOUIS HAHN. 



The hind limbs are of use chiefly for cHnging while at rest ; 

 the fore limbs form only an inadequate support for the animal 

 while at rest and they cannot be used at all for grasping as in 

 most mammals but, as in birds, they are the chief organs of 

 locomotion. 



Most insectivorous and carnivorous mammals use the paws to 

 assist in seizing and killing prey and, at times, rest their food 

 against some solid object while eating it. Bats, on the contrary, 

 seize their prey with the mouth, like swallows and flycatchers, 

 and the large, mobile lips assist in holding the food and drawing 

 it into the mouth. They usually masticate it while flying and do 

 not recover any portion that may be dropped. 



So greatly has this method of feeding modified the habits of 

 our common vespertilionine bats that the caged animals rarely 

 learn to take food from a dish or from the floor of the cage, 

 although they will eat it readily if it is held directly in front of 

 them. 



The expansion of the integument to form the flying mem- 

 branes has furnished additional surface for bearing organs of spe- 

 cial sense and according to Schobl ('71) a large number of tac- 

 tile organs are found in the skin of the wing membranes. The 

 nasal appendages and the tragus also have a sensory function, 

 the exact nature of which is not clearly understood. 



The nocturnal or crepuscular habit, which is shared by all 

 bats, is doubtless correlated with the increased number of sense 

 organs in the skin which makes the eyes of less importance to 

 the individual and enables it to be active in the absence of light. 



Throughout the order there is a relative uniformity of both 

 habit and form. A few species have white markings. In many 

 others the ventral side of the body is paler than the dorsal but 

 otherwise there is a great uniformity of coloration, the prevailing 

 color being some .shade of brown. I have seen almost as much 

 variation in the color of a single species from a restricted area as 

 there is in the entire order. While the details of tooth and 

 skeletal structure show that not all the members of the order are 

 closely related, yet the external forms of widely separated groups 

 resemble each other more closely than they do in some of the 

 more nearly related species of other orders. 



