88 BULLETIN 144, UNITED STATES NATIONAL MUSEUM 



which are free. Border of uropataguiin sprinkled with widely spaced 

 stiff hairs, scarcely visible without the aid of a lens. 



Foot. — The foot is strong, usually a little more than half the length 

 of the tibia, the ratio of its length to that of tibia averaging 51.2 

 in 10 specimens from Arizona, 53.4 in a like number from Michoacan, 

 and 54.1 in 9 from Lower California. Calcar well developed, and 

 terminating distally in a minute lobule, the skin along its free edge 

 thickened on the basal half but without forming a distinct keel. 



Fur and color. — The pelage is of moderate length, neither close nor 

 yet full and fluffy, the longer hairs on the back averaging about 6 mm. 

 in length, their tips not burnished. The general coloration is uni- 

 formly dull sepia or drab above, somewhat paler below, the bases of 

 the hairs everywhere dark except at the sides of the belly underneath, 

 where the hairs are whitish throughout. 



Skvll. — The skull is characterized by its broad rostrum, the area 

 of which, when skull is viewed from above, is not conspicuously less 

 than that of the brain case. (PI. 1, p. 7, fig. 6.) Distance from ante- 

 rior border of alveolus of inner incisor to narrowest region of inter- 

 orbital constriction about equal to that from constriction to lambda. 

 Breadth of rostrum across roots of canines greater than interorbital 

 constriction. Maxillary breadth at m^ (average in 20 specimens, 6.9) 

 nearly equal to breadth of brain case (average in 20 specimens, 7.2). 

 Brain case higher and narrower than that of Myotis lucifugiis. In 

 rear view the lambdoid crests are sharply defined. Seen from above 

 they form a sharp transverse ridge posteriorly which meets the well- 

 marked sagittal crest at the occiput and cuts off a raised triangular 

 area. In side view the rostrum appears nearly flat anteriorly ; behind 

 this region the forehead rises more abruptly than in Myotis lucifugus. 



Teeth. — In their general structure the teeth resemble those of 

 Myotis lucifugus. The secondary cusps and ridges (see fig. 1, p. 8) 

 are all fully developed but the cingulum is usually less distinct than 

 in the smaller animal. The hypocone tends to be lower relatively to 

 the protocone than is generally the case in M. lucifugus, a peculiarity 

 which is best appreciated when the teeth of the two animals are com- 

 pared from their lingual aspect. The greatest width of the palate 

 measured across the outer borders of the upper molars slightly ejc- 

 ceeds the maxillary tooth row (front of canine to back of vi^) and 

 is practically equal to or is at most minutely less than the mandibular 

 tooth row (exclusive of incisors). The maxillary rows of cheek teeth 

 as a whole are obviously more robust (broader in proportion to the 

 intervening area of palate) than is usual in other large American 

 members of the genus. This character can not be described with 

 sufficient definiteness to insure the identification of a single specimen 

 taken by itself, but it ig at once obvious on comparison of a few* 

 skulls of Myotis velifer with similar series of M. thysanodes or M. 



