72 Order CHIROPTERA 



The skull, slightly larger than that of any other Myotis in 

 Illinois, has an over-all length of 15.9-16.4 mm. (about Y% 

 inch) ; it has a pronounced sagittal crest. Dental formula: 

 I 2/3, C 1/1, Pm 3/3, M 3/3. 



Life History. — In summer, the gray bat sometimes congre- 

 gates in large numbers in limestone caverns of this state. With 

 the approach of cold weather, most bats of this species leave 

 these caverns for places unknown. A few, however, may hiber- 

 nate in the Illinois caverns. Very little is known about this bat 

 in Illinois, for it has been taken at only a few places. 



Distribution. — The gray bat is known in Illinois only from 

 Pike and Hardin counties, but it likely occurs throughout the 

 southern half of the state. No subspecies has been named. The 

 range of the species extends from eastern Kentucky and Ten- 

 nessee to western Missouri and northeastern Oklahoma, with an 

 extension in the east to northwestern Florida, fig. 50. 



MYOTIS KEENII (Merriam) 

 Keen's Bat 



Description. — Keen's bat is similar to the little brown bat 

 except that the ears are longer, fig. 5\b. When an ear is laid 

 forward, it extends 3 or 4 mm. beyond the tip of the nose. The 

 tragus in each ear is narrower and longer (about 9 mm. rather 

 than about 6 mm. long). The color of the fur on the under 

 parts is a buffier gray than in the little brown bat. 



Length measurements: head and body about \7/% inches 

 (47-48 mm.); tail l^-l^K inches (36-43 mm.); over-all 3%- 

 3l/2 inches (84—90 mm.) ; hind foot Y% inch (8-9 mm.) ; ear 

 from notch ^ inch (15-18 mm.). 



The skull is essentially as in the little brown bat. Its length 

 is 15-16 mm. (about jH$ inch). Dental formula: I 2/3, C 1/1, 

 Pm 3/3, M 3/3. 



Life History. — In Illinois, Keen's bat hibernates in caves 

 and mines. It is less gregarious than other species of Myotis \ 

 groups of a few individuals each hang apart from the larger 

 clusters of other kinds of bats in the hibernating chambers. 

 Although little is known of its "summer" habits, this bat appar- 

 ently is not colonial, and individuals find suitable abodes in such 

 places as mines, attics, crevices of buildings, and under eaves of 

 houses. 



