138 BULLETIN 144, UNITED STATES NATIONAL MUSEUM 



straight or concave. The lambdoid crests are transverse, sometimes 

 meeting at the occiput to form a sliort, backwardly directed angle. 



Teeth. — Molars proportioned to palate about as in Myotis liM)i- 

 fugus. The secondary cusps and ridges show an obvious tendency 

 to reduction; protoconule often less well developed than in Myotis 

 lucifugus, sometimes reduced to a mere thickening of the anterior 

 margin of the crown; metaloph usually present but rarely if ever 

 long enough to reach the crest of the ridge connecting protocone with 

 hypocone; cingulum as in M. lucifugus. The two small upper pre- 

 molars are nearly equal in cross-section; the posterior, however, is 

 slightly the smaller and about two-thirds the height of the anterior 

 tooth. They are usually both drawn slightly in from the tooth row, 

 the second commonly more than the first, though in some individuals 

 they are nearly in the row, and again the second may be so crowded 

 inward as hardly to be visible from the exterior. The premolars of 

 the lower jaw stand completely in the tooth row without crowding, the 

 first with a cross-section about one-third greater than the second, 

 which stands about two-thirds as high. As in Myotis lucifugus the 

 width of palate including the upper molars slightly exceeds the 

 length of the maxillary tooth row (front of canine to back of last 

 molar), and about equals the length of the mandibular tooth row 

 (excluding incisors). 



Remarks. — This species, though superficially resembling Myotis 

 lucifugus.^ is very distinct from other American bats. Its short 

 rounded ears, small foot, well-developed calcaral keel and obvious 

 extension of the fur on the ventral side of the membranes to a line 

 joining the elbow and knee, are characters which, combined, distin- 

 guish it at once externally. The skull is further diagnostic with its 

 shortened rostrum and large, high brain case, with the convex outlines 

 of the temporal ridges meeting at the occiput. 



Little is known concerning the habits of Myotis volans. It seems 

 to frequent open forest, ranging in summer to an altitude of at least 

 11,000 feet in the Sierra Nevada. Apparently it is not social to any 

 great degree and in general it seems to avoid caves. Dr. Joseph 

 Grinnell notes a specimen with a single fetus taken at Santa Rosa 

 Peak, Calif. ; a female from Anatone, Wash., June 23, also contained 

 a single young. 



The specimen on which Harrison Allen, in 1866, based his Vesper- 

 tilio volans was for many years lost sight of. The name was for a 

 time relegated to the synonymy of Myotis calif orrdcus (Miller, 1897). 

 It was not until 1914 that Goldman, on reexamining the type, found 

 it to be a representative of the species whose characters had been first 

 clearly indicated by True, in 1886, under the specific name longicrus. 

 Both names, however, remain in use, as they were applied to different 

 subspecies. Miller, in 1897, regarded this species as a form of Myotis 



