1914] Grinnell: Three New Races of VespertiUonid Bats 319 



Description. — The fur is distributed as in topotypes of M. y. 

 yumant nsis. On middle of back it averages about six millimeters in 

 length. Hairs everywhere clove brown at base; distal half of fur on 

 dorsal surface wood brown ; fur below light buff, with darker bases 

 of hairs showing through. On throat, sides and chin the color varies 

 toward warm buff; ears olive brown; feet, wings and tail-membranes 

 clove brown. The young are darker and grayer throughout, entirely 

 lacking the buffy tint of the adults. 



Measurements. — A series of five adult males of M. y. sociabilis 

 averages in millimeters as follows: Total length, 81.4 (75.0-87.0); 

 tail vertebrae, 33.3 (30.0-37.0) ; tibia, 15.2 (15.0-1G.0) ; foot, 8.1 (7.0- 

 10.0) ; forearm. 34.6 (32.9-35.3) ; greatest length of cranium, 13.7 

 (13.5-14.4) ; zygomatic breadth, 8.4 (8.0-8.6) ; breadth of braincase. 

 7.1 (6.7-7.6); interorbital constriction, 3.8 (3.5-3.9). 



Ten adult females from Old Fort Tejon, Kern County, average in 

 millimeters as follows: Total length, 81.9 (76.0-85.0); tail vertebrae. 

 36.6 (34.0-37.0) ; tibia, 14.7 (13.5-16.0) ; foot, 8.9 (8.0-10.0) ; fore- 

 arm. 34.2 (33.7-35.0); greatest length of cranium, 13.8 (13.4-14.2); 

 zygomatic breadth, 8.1 (7.8-8.3) ; breadth of braincase, 7.2 (6.7-7.3) ; 

 interorbital constriction, 3.7 (3.6-4.0). 



Specimens examined. — Total number sixty-nine, from the follow- 

 ing localities in California : Butte County — Chambers Ravine, four 

 miles north of Oroville, 1 ; Glenn County — "Winslow, five miles west 

 of Fruto. 1; Kern County— Old Fort Tejon, 61, Buttonwillow, 1 

 (Calif. Acad. Sci.) ; San Bernardino County — Bluff Lake, 7500 feet 

 altitude, 3, Bear Lake, 6700 feet altitude, 1, South Fork Santa Ana 

 River, 8500 feet altitude, 1. 



Remarks. — Specimens of M. y. sociabilis from the San Bernardino 

 Mountains show strong superficial resemblance to the smaller indi- 

 viduals among a series of Myotis longicrus (True) from the same 

 locality. The longer tibia of the latter species, however, together with 

 the slightly greater size of skull and the more elevated occipital region, 

 serves to allocate individuals. 



Distribution. — The distribution of this bat cannot be stated with 

 confidence without much further field-work. It appears to occupy an 

 intermediate geographic position between that of M. y. yumanensis 

 and .1/. y. saturatus, namely the semi-arid Transition and Sonoran 

 zones in California west and north of the southeastern deserts. 



