66 BULLETIN 43, UNITED STATES NATIONAL MUSEUM. " 



niiues at ii i)oiutiiot far remote from the vampyriiie group, or the uu- 

 kiiowii ancestral stem of Natalus and Thyroptera. 



1. Antrozous pallidus (Leconte). The pale bat. (Plates viii, ix.) 



Vespertilio pallidus Leconte, Proc. Acad. Nat. Sci. Phila. vii, 1855,43; Baird, U. S. and 



Mex. Bound. Survey, Report ii, 1858, PI. i, Fig. 1. 

 J ntrozo us jHill id i(s 11. AUen I.e.; Dobson, Cat. CUirop. Brit. Mus., 1878, 170; Cones, 



Amer. Nat., 1867, 283; Cones and Yarrow, Wheeler's Exped., Zoiil., 1875,85. 



Diagnosis. — Scallops of auricle not breaking convex outline of outer 

 margin; external basal lobe concealed in part. The vespertilionine 

 tragus half the height of the auricle. Head folds continuous on the 

 dorsum. Transverse ridge defines the upper border of the blunt muzzle. 

 The nostrils simple, lunate. Ohin plate subtriangular, defined. In- 

 cisors in lower jaw, four in number. Protocone rudimental ; last maxil- 

 lary molar but half the size of others and composed of rudimental pro- 

 tocone and paracone. Proximal rudiment of the ulna not anchylosed 

 to radius at elbow. Muzzle glands flat, nearly confluent above. The 

 second and third metacarpals distinct on j^almar surfaces. Phalanges 

 of the third digit of one length; the first phalanx of the fourth and 

 fifth digit longer than the second. A well-defined hem of membrane is 

 seen between the thumb and second digit; the fifth digit greatly longer 

 than the forearm. The terminal cartilage of the fourth digit deflected 

 toward the second digit. Numerous closely arranged muscle fibers 

 arise from the tibia near the oblique tibial line and are dispersed over 

 the greater part of the membrane nearly to the fifth digit. * The ole- 

 cranon is dorsal, the membranes arising from the epicondyle. The sec- 

 ond and third metacarpals are not on level of membrane, but raised 

 above it, and not crossed by oblique lines. This easily distinguishes 

 Antrozous from other genera of Vespertilionidiie.t 



The manal formula is as follows: 



Secon d interspace 3 



Third interspace 15 



Foiirth interspace 28 



Forearm 51 



The greater part of the free margin of wing membrane with a delicate 

 butt" border. This is not peculiar, but appears to be unusually con- 

 spicuous. 



The tail is raised from the plane of the undersurfiice of the interfem- 

 oral membrane near the pubis, but for the rest of its length it is raised 

 from the dorsal. The terminal joint is exsert, and bears a small fleshy 

 tip. The calcar is longer than the foot and ends in a small lobe. The 

 post calcaral lobe is fleshy and obscurely defined. The interfemoral 

 membrane is crossed by numerous broad transverse lines. 



''The accessory cartilage must be sought for with care by the aid of a powerful 

 lens. 



+The statement of E, Coues that the second digit has two phalanges is not con- 

 firmed. 



