A MONOGRAPH OF THE IJATS OF NORTH AMERICA. 181 



The closely allied Pro mops perotis should be carefully compared with 

 the foregoing subspecies. It presents the following characters: 



Ears not as high as broad. Thick at tlie large keel and in the region 

 of the junction of the keel with the upper base; for the rest, thin and 

 membranous. Hence the ear lies in the head in an irregular mass of 

 folds. The second scallop not easily distinguished from the concli. 

 By careful inspection a small incision is seen to lie on the outer margin 

 at beginning of the ridge of the external basal lobe and the upper mar. 

 gin of the auricle. The second scallop cannot be traced beyond the 

 post-antitragus notch. The posterior border of the auricle is without 

 emargination. The keel is much wider than in P. californicus. The 

 rausverse auricular line not in the form of ridges. The second scallop 

 does not reach the antitragus, which has the same form as in P. cali- 

 fornicus. The notch of the interauricular membrane is without tuber- 

 cles. The snout with lesfe shari> margin and apparently no median 

 vertical ridge. The interauricular membrane with septum 0""" behind 

 muzzle and G""" in front of skull. Thus, tlie membrane lies uiDon the 

 movable snout. 



Antitragus twice as long as high; ridge extending forward joining 

 the upper lii) in advance of the angle. Keel fleshy, with lower third 

 forming a lobe which is folded backward and touching the rudimental 

 external basal lobe. A consj)icuous fringe of short hair grows from 

 conch on line of the keel. The ears are joined by a membrane, which 

 is 3™'" high, and lies on the snout directly back of the muzzle. It 

 is folded back, excepting at the median line. This membrane, together 

 with the band for two-thirds of the posterior surface of the auricle, are 

 thickly covered with hair. A fringe of small hairs border the auricle 

 a1)ove the second scallop. 



The tragus is twice as high as wide; nearlj'^ rectangular apex and 

 without l)asal notch and lobe. The long mobile snout is one-fourth 

 the length of the head. The upper margin of the muzzle is not found 

 by the convex contour line as in Nyctiuomus, but presents above it a 

 triangular cushion, which is surrounded by long, thick hair, wlii(;h tills 

 in the interspace between the muzzle and the interauricular membrane. 

 The upper lip is separated from the muzzle by a fringe of hair. The 

 rictus (angle of the mouth) lies in a lino with the eye. 



The terminal phalanges of the manus are described as follows: Third 

 digit, terminal phalanx compressed laterally; apex slightly expanded, 

 triangular; no membrane on the ectal side. Fourth digit, terminal 

 phalanx .slender, aciculate, witliout free tip, and inclined pollical. Fifth 

 digit, the terminal phalanx is broad, almost spatulate, the proximal 

 half thickened, the endopatagium is attached to the base, and the mem- 

 brane of the fourth interspace to its tips. 



The brain. — The cerebellum is provided with a flocculus. The cere- 

 brum is pyriform, smooth. 



Sex differences. — The hair is of a brownish shade, darker in the female 



