12. Total length about four inches; color usually rust'red, sometimes yellowish' 



gray 



Lasiurus horealis (Miiller) Red Bat 

 (J^ycteris horealis (Miiller) ) 

 Total length about five inches; color gray, with hairs of back dark at base, 

 fading to silvery at tips 



Lasiurus cinereus (Beauvois) Hoary Bat 

 (Islycteris cinerea (Beauvois) ) 



13. Ear short and wide, with a short, broad tragus almost as wide as high; 



color blackish-chocolate, with some hairs white-tipped; generally dis- 

 tributed 



Lasionycteris noctwagans (Le Conte) Silvery-haired Bat 

 Tragus about twice as high as wide; color not hoary 14. 



14. Fur light yellowish or yellowish-gray; glandular area on each side of 



snout practically bare; usually less than three and one-half inches in 



total length 15. 



Fur usually brownish, except sometimes in dry habitats; sides of mu2;2;le 



with hair; usually three and one-half inches or more in length 16. 



15. Tragus with widest part just below the tip, which is inclined forward; 



from western Texas westward 



Pipistrellus hesperus (Allen) Western Pipistrelle Bat 

 Tragus with widest portion near base; tip not inclined forward; from 

 the eastern states to Iowa and Texas 



Pipistrellus suhflavus (Cuvier) Georgian or Pipistrelle Bat 



16. Profile almost straight; tragus short and blunt, curving noticeably for- 



ward; with one upper incisor on each side; west to Texas 

 Jslycticeius humeralis (Raf.) Rafinesque's Bat 

 Profile of head concave ("dished in" portion can be felt with the finger 

 tip, although the hair conceals it), or sometimes almost straight; tragus 

 not curving decidedly forward; with two tiny incisors on each side 17. 



17. Interfemoral membrane bare; hair long, usually almost half an inch on 



the back; getting to be four and one-half inches in total length; gener- 

 ally distributed 



Eptesicus fuscus (Beauvois) Big Brown or House Bat 



(Vespertiho fuscus Beauvois) 



Interfemoral membrane furred about one-quarter of the way down; hair 



about one-quarter of an inch long; smaller; My otis or Little Brown 



Bats (A difficult group, with many subspecies. For revision of this 



genus, see Miller and Allen, 1928, U. S. Nat. Museum, Bull. 144.) 18. 



18. Hair on back of uniform color, not much darker at base; wing membrane 



attached at ankle; central states 



MyoUs grisescens Howell Cave Bat 

 Hair on back definitely darker at base; wing membrane attached at base 

 of toes 19. 



19. Free edge of interfemoral membrane very distinctly hairy; in the western 



states 



Myotis thysanodes Miller Fringed Bat 



484 



