﻿LASIURUS BOREALIS. 



107 



Membranes. — The flight membranes are attached at base of toes, the 

 nropatagium at extreme tip of tail. 



Feet. — The foot is small, less than half as long as tibia. Dorsal snr- 

 face of toes thickly furred. Oalcar about twice as long as foot and con- 

 siderably shorter than free border of interfemoral membrane. It is 

 slightly develoi^ed, indistinctly keeled, and seldom lobed at tip. 



Fur and color. — The fur is everywhere full and soft. On middle of 

 back it is about 7 mm. in length and on neck about 10 mm. It covers 

 the basal two-thirds of dorsal side of ear, the whole dorsal side of the 

 interfemoral membrane, and the dorsal side of the flight membrane to a 

 line running from ankle to middle of humerus. There is a narrow strij) 

 of fur running along basal third of fifth metacarpal and a squarish 

 clump at base of thumb. Kear base of forearm (in position occupied 

 by strip of fur in L. clnereus) there are numerous fine scattered hairs, 

 which are so inconspicuous as readily to escape notice. On the ventral 

 surface the fur reaches about to middle of nropatagium and on flight 

 membranes to line joining knee and elbow. Beyond elbow a sparse 

 growth of hairs covering an area 10 mm. or more in width extends 

 along forearm to bases of fingers, where it 

 becomes much more dense. The ante- 

 brachial membrane is covered with a sparse 

 coating of hairs on the ventral surface. 



In color typical Lasiurus horcaUs varies 

 very extensively, but never shows the ma- 

 hogany brown of seminoluHOT the intense red 

 of the tropical races. Red specimens are ru- 

 fous red throughout (the exact shade some- 28.-Top view of sknii of {a) Lasi. 

 where between rutous and burnt siennaj, 



paler and more fawn-colored on the belly, the hairs of the back usually 

 with distinct grayish tips, those on the throat and chest tipped w ith 

 whitish. A yellowish white patch in front of each shoulder. Frequently 

 the white on chest tends to connect the shoulder patches by a whitish 

 collar. The individual hairs on the back are blackish at base, then 

 light rufous to the narrow subapical band which gives the characteris- 

 tic color to the back, and, finally, grayish white at extreme tips. Gray 

 specimens are yellowish gray on the back and bufly on the belly. The 

 red usually persists as a faint salmon sufl'usiou. 



SlcnU. — The skull of typical Lasiurus horealis (figs. 28 a, 29 h) has 

 the broad rostrum and flaring zygomata of L. cinereus. The dorsal 

 profile of the skull is nearly straight from external nares to highest 

 point of occiput. The skull of an adult female from Washington, D. 0,, 

 measures: Greatest length, 13.8 5 zygomatic breadth, 10.2; breadth of 

 rostrum at posterior edge of large premolar, 6; mandible, 10; upper 

 tooth row, 5.4; lower tooth row, 0.4. 



Teeth. — The teeth (fig. 30 h) are large, the upper molars broad on the 



