150 BULLETIN 144, UNITED STATES NATIONAL MUSEUM 



on the upper part of the posterior border, below which it is nearly- 

 straight to the basal shoulder which stands off gradually instead of 

 projecting abruptly (as in Myotis yumanensis) . The tragus is nar- 

 row, its inner margin straight, and equaling one-half the entire 

 height of the ear (6 mm.) ; the region of its greatest width is slightly 

 above the level of the inner base, whence the posterior margin is 

 gradually beveled to the acute tip. There is a shallow emargination 

 opposite the inner base, below which is a small rounded lobe. 



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

 of the foot at the base of the toes, just below the ends of the meta- 

 tarsals. The third to fifth metacarpals are very slightly graduated 

 or the third and fourth may be almost equal in length. Taking the 

 third finger as 100, the fourth and fifth fingers are respectively about 

 as 86 and 79 (58: 50:46 mm.). When the wing is folded the end of 

 the third metacarpal usually comes quite to the elbow (or rarely 

 exceeds it, or falls 0.5 to 1 mm. short) ; that is, the length of the 

 third metacarpal about equals that of the forearm. The tip of the 

 tail is free. The fur of the body extends slightly on to the mem- 

 branes, especially on the intertibial part of the uropatagium where 

 there are numerous scattered hairs dorsally. 



Foot. — The foot is small, slender, and weak, its length normally 

 less than one-half that of tibia (average ratio of foot to tibia in 10 

 specimens from the Northwest Coast, 46.6; in 10 from Point Reyes 

 and Nicasio, Calif., 43.1; in 10 from Lower California, 43.4; and in 

 10 from Patzcuaro, 44.9). The calcar is less than the length of the 

 free border of the uropatagium (about 13:15 mm.) and ends in a 

 projecting lobule. Its edge usually bears a well-developed keel which 

 rises abruptly at about the length of the metatarsus from the heel, 

 and gradually tapers off. 



Fur amd color. — The pelage is long, full, and of fine texture, the 

 hairs with long silky ends which, however, are dull, rarely burnished. 

 The tips of the hairs are usually brown or yellow in tone, strongly 

 contrasting with their slaty bases both above and below. The dorsal 

 side of the uropatagium is well though thinly haired between the 

 tibiae above, but not quite to one-half their length below. On the 

 ventral side the fur extends sparingly outward as far as a line join- 

 ing the knee and the elbow. 



Skidl. — The skull (pi. 1, p. 7, fig. 14) is delicate and slender, with 

 relatively long and tapering rostrum, about 3/7 of the total length of 

 the skull. The profile of the rostrum rises rather sharply to the 

 forehead and decidedly flat-topped brain case. Sagittal crest usually 

 inconspicuous or absent. Lambdoid ridges distinct though low. 



Teeth. — In general the teeth resemble those of Myotis evotis re- 

 duced in size proportionately to the smaller skull. Upper molars 



