AMERICAN BATS OF THE GENERA MYOTIS AND PIZONYX 123 



fornia and Arizona 80.9, in 10 from New Mexico 75.2, and in 10 

 from San Luis Potosi 76.5) ; ear less enlarged (usually about 16 

 to 18 mm. in length) ; foot relatively longer (ratio of its length to 

 that of tibia usually more than 50) ; and fringe of hairs along free 

 border of interfemoral membrane well developed and conspicuous. 

 Maxillary tooth row about 6.5 mm. in length, exceeded by the 

 greatest width of palate including molars. 



Ears, — The ears are elongated, when laid forward reaching from 

 3 to 5 mm. beyond the nose. Tragus long and slender, about 60 per 

 cent of the height of the ear, its anterior border very slightly convex. 

 The posterior border has a distinct squarish lobule at its base, suc- 

 ceeded by a right-angled notch, above which the outline is at first 

 convex with a slightly crenulate edge, then faintly concave below 

 the tip. 



Wing and jnembranes. — The wing membrane arises from the side 

 of the foot near the base of the toes. The third and fourth meta- 

 carpals are usually nearly equal, while the fifth is a trifle less, but 

 there is a slight tendency for the fifth to be of equal length with 

 the fourth. When folded, the third metacarpal falls about 1.6-2 

 mm. short of the elbow and is thus proportionately longer than in 

 Myotis evotis in which the discrepancy is about the same but the 

 forearm is shorter. Taking the third finger as 100, the fourth is 82, 

 and the fifth 79 ; proportions which are essentially like those found in 

 M. evotis. The minute terminal joint of the tail alone is free from 

 the membrane. Free edge of the uropatagium bordered both above 

 and below by a conspicuous fringe of short stiff hairs which occur 

 in small tufts or clumps, about 15 hairs to each tuft. This fringe 

 is usually quite evident to the eye without the help of a lens. 



Foot. — The foot is proportionally larger than in Myotis evotis, its 

 length usually more than half that of the tibia. In 9 topotypes the 

 ratio of foot to tibia averages 53.7 ; in 10 specimens from New Mexico 

 it averages 55.2; in 10 from San Luis Potosi, 53.3; and in 6 from 

 Oaxaca, 56.9. Calcar heavy, without distinct keel, but the skin along 

 its free margin is thickened and compressed to an evident edge. It 

 terminates distally in a minute lobule. 



Fur and color. — The pelage is full and rather long, the hairs about 

 9 mm. in length at the middle of the back. The hair is dark at the 

 base with slightly buff tips above, and whitish tips below, that at 

 the sides of the abdomen without dark bases. 



Skull. — The skull resembles that of Myotis evotis but is immedi- 

 ately distinguishable by its greater size, better developed sagittal 

 crest, less inflated auditory bullae, and less narrowed rostrum (ratio 

 of greatest breadth across molars to condylobasal length about 44 

 instead of about 40; greatest breadth across molars usually much 

 greater than length of maxillary tooth row) ; mandible obviously 



