AMERICAN BATS OF THE GENERA MYOTIS AND PIZONYX HI 

 MYOTIS EVOTIS (H. Allen) 



(Synonymy under subspecies) 



Distribution. — From Vera Cruz and Lower California north to 

 southern British Columbia, thence eastward in the arid portions of 

 the United States to Colorado and North Dakota. 



Diagnosis. — Like Myotis keenii but slightly larger (forearm 

 usually 37 to 41 mm.; greatest length of skull 15.0 to 16.4 mm.) and 

 with longer tail (average ratio of tail to head and body in 4 speci- 

 mens from the northwest coast 90.3, in 10 from Colorado 96.9) and 

 much larger ear (height from meatus usually more than 20 mm.). 

 Auditory bullae slightly enlarged; a small and rather inconspicuous 

 sagittal crest nearly always present in adults; crown area of upper 

 cheek teeth distinctly greater than in M. keenii (crown of m ^ usually 

 about 1.45 to 1.50 by 1.95 to 2.00 mm.). A thin and inconspicuous 

 fringe of minute hairs along the free border of the interf emoral mem- 

 brane. 



Ears. — The ears are long, when laid forward extending 5-7 mm, 

 beyond the tip of the nose (in alcoholic specimens). Tragus corre- 

 spondingly long, about 47 per cent of the height of ear (9:19 mm.), 

 slender, tapering; its inner border is nearly straight, bending 

 slightly outward at the tip. A small rounded lobe is at its outer base, 

 succeeded by a distinct notch, above which is the broadest point. 

 The outer margin is very slightly convex basally then very faintly 

 concave toward the top. The intense black color of the ears usually 

 persists in dried specimens. 



Wing and msTribranes. — Wing membrane from the base of the toes. 

 Metacarpals 3, 4, and 5 usually about equal in length ; sometimes the 

 third is a very little longer than the others. When folded, the third 

 metacarpal reaches to within 2 mm. of the elbow. The fourth and 

 fifth fingers are of nearly equal length; taking the third as 100, the 

 fourth is 83, the fifth 82 (61:51:50 mm.). Terminal vertebra of 

 the tail free. The free border of the uropatagium is thinly fringed 

 above and below with minute hairs; these are usually not obvious 

 without a lens, yet they project beyond the edge and grow in little 

 clusters of from 2-4. This fringe is much less developed than in 

 Myotis tJiysanodes, yet it is often perfectly definite; and even when 

 no true fringe is formed the presence of numerous scattered hairs 

 along the free border of the membrane is usually characteristic of 

 M. evotis as compared with M. keenii. 



Foot. — The foot is proportioned to the tibia nearly as in Myotis 

 keenii; that is, it is usually somewhat less than half as long as the 

 tibia, but is not infrequently more than half as long. In 10 specimens 

 from the northwest-coast reeion the ratio of foot to tibia averages 



