﻿56 



NORTH AMERICAN FAUNA. 



sharea by no other American genus of Vespertilionidw, are usually 

 recognizable by tlieir slender forms, long tails, hairy ftices, narrow ears, 

 and tapering, straight, or recurved tragi. As I have had no opportu- 

 nity to study any of the Old World species except M. myotis, I can 

 make no attemx)t to define the genus in detail, but the dental formula, 

 coupled with the characters of the family, is sufficient to distinguisli 

 the genus among American bats. The species of Myotis differ greatly 

 among themselves, especially in size (see figs. 11 and lli). Ifc may 

 eventually prove necessary to divide the genus into two or more sub- 

 genera. 



KEY TO NOKTH AMERICAN FORMS OF MYOTIS. 



Free border of nropatagiuin conspicuously fringed thysanodes (p. 80) 



Free border of uropatagium not conspicuously fringed. 

 Forearm more than 40 mm. 



Ear wben laid forward extending barely beyond nostril velifer (p. 56) 



Ear wben laid forward extending 7 to 10 mm, beyond nostril erotis (p. 77) 



Forearm less than 40 mm. 



Ear when laid forward extending 7 to 10 mm. l)eyond nostril evotis (p. 77) 



Ear when laid forward extending less than 6 mm. beyond nostril. 



Fur on back not distinctly bicolor nigricans (p. 74) 



Fur on back distinctly bicolor. 

 General color whitish gray. 



Foot 8 to 10 mm yumanensis (p. 66) 



Foot 5 to 7 mm ciliolahrum (p. 72) 



General color never whitish gray. 

 Forearm 30 to 35 mm. 



Color light yellowish gray calif ornicus (p. 69) 



Color yellowish brown. 



Forearm 31 to 33 mm caurinns (p. 72) 



Forearm 32 to 36 mm mexicanus (p. 73) 



Forearm 34 to 40 mm. 



Tibia less than 15 mm saturatus (p. 68) 



Tibia 15 to 19 mm. 



Ear and tragus slender, the latter 9 mm. or more in length. 



Color light brown suhulaius (p. 75) 



Color blackish leeuii (p. 77) 



Ear and tragus short and broad, the latter 8 mm. or less in length. 



Tibia 17.5 to 20 mm longicrus (p. 64) 



Tibia 15 to 17 mm. 



Ear 12 to 14 mm Jucifngns (p. 59) 



Ear 14 to 16 mm alascensis (p. 63) 



MYOTIS VELIFER (J. A. Allen). 



1890. Vespertilio velifer J. A. Allen, Bull. Am. Mus. Nat. Hist., N. Y., HI, p. 177, Dec. 10, 

 1890. 



1896. Vespertilio incautus J. A. Allen, Bull. Am. Mus. Nat. Hist., N. VIII, p. 239, Nov. 

 21, 1896. (Texas.) 



Type locality. — Santa Oruz del Yalle, near Guadalajara, Jalisco, 

 Mexico. 



Geographic distribution. — Near border line between upper and lower 

 Sonoran zones from Missouri and Indian Territory soatli to Hidalgo, 

 northern Miclioacan, and the City of Mexico. 



