252 



BULLETIN 5*7, UNITED STATES NATIONAL MUSEUM. 



not forming noticeable secondary cusps, except occasionally at pos- 

 terior base of lower tooth. First upper premolar {pm -) minute but 

 perfectly in tooth row and not specially crowded. Second upper pre- 

 molar (pm 1 ) not in contact with canine, well developed, and with 

 large antero-internal cusp. Lower premolars normal in form" and 

 size, the first not as high as second, but with the cross section nearly 

 as great. Molars normal; m x and m 2 with inner segment large", the 

 terete hypocone unusually distinct ; m 3 with crown area more' than 

 half as great as that ofm'orm 2 and about equal to that of pm 4 ; 

 the metacone and three commissures well developed. Lower molars 

 with all the cusps normal in size and form, the three inner approxi- 

 mately equal in height. Skull (figs. 41^3) with rounded or some- 



Fig. 41. — Nyctinomus brasiliensis. 

 Parana, Brazil. No. 37873. x 2. 



Fig. 42.— Nyctinomus europs. Adult fe- 

 male. Brazil. Paratype, No. 101502. >:2£. 



what flattened, moderately wide brain case about one and one-third 

 times as long as rostrum, above level of which it is very slightly ele- 

 vated, and at least half as deep as wide; a distinct depression in 

 front of occipital region ; sagittal crest scarcely indicated ; lachrymal 

 and supraorbital ridges low but evident; dorsal surface of rostrum 

 with faint longitudinal concavity between orbits; zygoma slightly 

 expanded at middle. Anterior palatal emargination about as large 

 as base of canine, wider posteriorly than between incisors; palate 

 slightly arched, but nearly flat antero-posteriorly ; pterygoids paral- 

 lel ; basisphenoid pits moderately developed or obsolete. Ears large 

 and rounded, arising from same point on forehead. Laid forward 

 they extend distinctly beyond extremity of muzzle; anterior border 

 of ear conch with 6 to 8 horny excrescences; keel well developed: 

 tragus small, flattened, squarely truncate above; antitragus variable 



