FIELD BOOK OF MAMMALS 



tragus reduced but antitragus generally very large; fifth finger 

 greatly reduced ; wing membranes strong, thick, and leathery ; 

 the interfemoral membrane narrow, especially so when com- 

 pared to the Vespertilionidae ; wing surface narrow; tail pro- 

 jecting noticeably beyond interfemoral membrane and earning 

 for this group the name of "Free-tailed" Bats; dentition of 

 normal insectivorous type. 



This family occupies among American Bats a position more 

 or less analogous to that occupied by the Swifts among the 



Fig. 1 6. Free-tailed Bat 



birds, as far as outward manifestations of flight ability are 

 concerned. The Free-tailed Bats, with their narrow, pointed 

 wings, progress through the air with rapid wing beats which 

 appear to travel through a rather restricted arc. Flight is 

 very rapid and very erratic, and these Bats can be recognized 

 as molossids almost as far as they can be seen. Some of the 

 species (of the genera Molossus and Tadarida) take wing very 

 early in the evening, often in the late afternoon. 



This family is much more tropical in its distribution than the 

 Vespertilionidas and only a very few forms range far enough 

 north to enter the United States. The molossids that reach 



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