1918] Grinnell: A Synopsis of the Bats of California 301 
Limbs and Membranes.—Wines moderately slender; third meta- 
carpal slightly longer than fifth. Wing membranes attached to bases 
of toes. Interfemoral membrane reaching to tip of tail. Foot slen- 
der, somewhat compressed, and about half length of tibia. Calear 
distinct and extending along edge of interfemoral membrane for about 
a quarter of the distance from its origin to tip of tail. 
Pelage.—Face nearly naked save for about a dozen slende hairs, 
5 millimeters in length, which arise from the glandular masses on 
sides of rostrum. Hair on top of head short, being only abont 2 
millimeters in length; elsewhere on the body it is from 5 to 8 milli- 
meters in length and very silky in texture. Kars naked, as also 
the wings, save for a narrow strip of hair continuous with body fur. 
Interfemoral membrane seantily haired over proximal half of its 
dorsal surface; upon its ventral surface the hairs are even less plenti- 
ful. Dorsal surface of toes well furred. 
Color.—The fur varies from deep blackish chocolate, tipped with 
silvery white, to a decided brownish, tipped with yellowish gray. 
Seton (1909, p. 1167) states that he has in his collection an old 
female silvery-haired bat, taken in New York State, which is brownish 
black everywhere, with no trace of the silver tippings. A male in 
the Museum of Vertebrate Zoology (no. 13802), taken August 4, 
1911, on Kangaroo Creek, Siskiyou County, California, has the mem- 
branes and the basal part of the fur everywhere blackish. On the 
back, belly, and interfemoral membrane the hairs are tipped with 
silvery white. On the face, crown, throat, and a patch over each 
shoulder the silvery tips are lacking. This specimen, as evidenced 
by the thin, papery skull and the prominent joints of the fingers, is 
a juvenal. Merriam (1884, p. 191) states that the young alone possess 
the perfect silvery tips to the hairs and that even before going into 
winter quarters for the first time their pelage has assumed the grizzled 
appearance which characterizes the coats of the adults. 
Skull and Teeth—The skull and teeth have been sufficiently de- 
scribed under the characterization of the genus (see p. 299). 
Average Measurements.—A series of 12 specimens of the silvery- 
haired bat, including both sexes, averages in millimeters as follows: 
total length, 102.0 (extremes, 92.0-107.0) ; tail vertebrae, 41.1 (34.0— 
44.0); tibia, 15.8 (14.0-18.0); foot, 10.0 (9.5-10.0) ; forearm, 39.2 
(37.3-42.0) ; greatest leneth of cranium, 16.1 (15.5-16.5). 
Synonymy and History.—The silvery-haired bat was first de- 
scribed by Le Conte (1831, p. 31) from a specimen from the ‘‘ Kastern 
United States’? under the name V{[espertilio|. noctivagans. Peters 
(1865, p. 648) made this bat the type species of his new genus 
Lasionycteris. 
Distribution.—Miller (1912, p. 60) gives the general range of 
Lasionycteris noctivagans as ‘‘North America north of Mexico, from 
the Atlantic to the Pacific; probably not breeding south of the 
Transition Zone.’’ The range in California lies altogether within 
the northwestern portion of the state, and for the most part within 
the Transition Zone. (See map, text-fig. O.) 
