138 BULLETIN 51, UNITED STATES NATIONAL MUSEUM. 



Upper incisors well developed, distinctly projecting forward and 

 forming a continuous row almost from canine to canine (the dia- 

 stema less than width of outer incisor) . Crown of inner tooth longer 

 than high, the cutting edge straight, slightly oblique, the posterior 

 surface flat and almost parallel with anterior surface. Outer tooth 

 shorter, though with cutting edge in line with that of inner, its 

 crown more oblique, though of about the same area. Lower incisors 

 well developed, completely or nearly filling space between canines, 

 the crowns very low and about as broad as long, the outline roundish 

 or subquadrate, the upper surface with a faint median ridge. 

 Canines strong, simple, with slightly developed cingula and no 

 secondary cusps, the upper with distinct anterior and posterior cut- 

 ting edge. Upper premolars with narrow trenchant crowns, longer 

 than high, triangular in outline when viewed from the side, the 

 main cusp slightly in front of the middle, the styles obsolete. First 

 and second lower premolars similar, but with lower crowns; third 

 with crown distinctly widened posteriorly. First and second upper 

 molars with nearly half of the crown occupied by a conspicuous 

 pit-like depression on the inner side of which is the narrow but 

 distinct protocone, and on the outer side the paracone, metacone, 

 and mesostyle. Parastyle and metastyle small, and commissures 

 low; this, together with the distinct pushing outward of the para- 

 cone and metacone causing a noticeable flattening and widening of 

 the W -pattern. Third upper molar with crown area more than 

 half that of second, the median depression well developed, as are 

 the protocone, paracone, and elongated, low parastyle; mesostyle 

 and metacone somewhat reduced, and the three commissures distinct. 

 Inner border of all three molars strongly convex. Lower molars with 

 the usual five cusps present and distinct, the three teeth alike in form, 

 but the last slightly smaller than either of the others. "While the 

 cusps are well developed the commissures are obsolete, giving the 

 crowns a peculiar multituberculate appearance when viewed from 

 above. Skull with braincase large and elongate, but low, rounded 

 and smooth. Rostrum somewhat shorter than braincase, low and 

 weak. A small but distinct lachrymal inflation. Basisphenoid pits 

 distinct but shallow. Audital bulla; small, covering less than half 

 surface of cochlea?, their greatest diameter slightly more than width 

 of basioccipital. Tail not as long as tibia, extending barely to middle 

 of broad interfemoral membrane. 



Species examined. — Gloxxophaga ant ill arum (Rehn), G. elongata 

 Miller, G. loiie/iroxfrk Miller, G. miifica Merriam, G. soricina 

 (Pallas), and G. trvei H. Allen. 



