PIPISTRELLUS. 583 
Geogr. Distr. Lower California, Mexico, to western Texas. 
Genl. Char. Size small; ear reaching to nostril, short and rounded 
at tip; tragus curved forward at tip; end of tail free of membrane. 
Color. Light yellowish gray, hairs plumbeovs at base; between 
fourth and fifth finger, the border of wing membrane is whitish; ears, 
face muzzle, and membranes black. 
Fic. LXXXVI. ° PIPISTRELLUS HESPERUS. 
No. 10851 Field Columbian Mus. Coll. Trifle more than twice nat. size. 
Measurements. Total length, 72.8-79; tail vertebre, 28-34.5; 
tibia, 11-12.8; foot, 5-6; forearm, 28-32.5; thumb, 4; longest finger, 
4855.5; ear from meatus, 10-12.4; width of ear, 8.6-9.6; tragus, 
4.6-5.4. Skull: occipito-nasal length, 11; zygomatic width, 7; width of 
braincase, 6; occipital depth, 4. 
a.—apus (Prpistrellus), Elliot, Pub. Field Columb. Mus., 111, 1904, 
p- 269. Zodlogy. 
Swirt Bat. 
Type locality. Providentia Mines, State of Sonora, Mexico. 
Genl. Char. About the size of P. hesperus, but quite different in 
color, and with a larger foot. Larger than P. h. australis, the exact 
color of which is not known. 
Color. Upper parts wood brown, base of fur blackish; under 
parts pinkish brown; nose, space before and around eyes, wing, and 
tail, membranes, feet, and ears black. 
forearm, 30.5; thumb, 4; longest finger, 47; ear from meatus, ro. 
Skull: occipito-nasal length, 10.5; zygomatic width, 8; interorbital 
constriction, 3; width of braincase, 6.5; palatal length, 5; post-palatal 
length, to anterior rim of foramen magnum, 4; length of upper tooth 
Measurements. Total length, 72; tail vertebre, 31.7; foot, 6.3; 
