PIPISTEELLUS 207 



inflated, the inflated region with a median angle suggesting 

 a rudimentary postorbital process ; rostrum short and broad, 

 narrowing gradually in front, a slight concavity at each side 

 bordering lachrymal inflation, and an evident median longi- 

 tudinal groove, most noticeable posteriorly ; nasal emargina- 

 tion slightly deeper than wide, extending less than half way to 

 interorbital constriction ; anteorbital foramen small, over point of 

 contact between large premolar and first molar ; palate broad, 

 distinctly concave both longitudinally and laterally ; anterior 

 emargination small, wider than deep, its posterior border on line 

 with posterior edge of canine ; mesopterygoid fossa squarish, 

 encroached on anteriorly by broadly triangular median palatal 

 spine ; hamulars slightly turned inward. Mandible robust, the 

 ramus much deeper at symphysis than behind tooth-row, the 

 coronoid process so low that upper edge of posterior portion of 

 mandible is squarely and horizontally truncate, parallel with 

 alveolar line ; angular process short but well developed, on level 

 with alveolar line, its extremity slightly bent inward. 



Teeth. — Relatively to size of skull the teeth are rather large 

 and robust, though inclined to be low, tendencies especially 

 noticeable in the canines. Inner upper incisor robust, its shaft 

 nearly half as high as that of canine, and directed strongly 

 forward and slightly inward, its crown irregularly elliptical-oval 

 in outline, with main axis nearly in line of tooth-row ; secondary 

 cusp large and conspicuous, about half as high as main shaft, 

 from the postero-external surface of which it projects ; cingulum 

 well developed, often forming a minute postero-basal cusp. Outer 

 upper incisor slightly but evidently smaller than inner, its shaft 

 more than half as high as that of inner, to secondary cusp of 

 which its extremity is closely approximated ; crown outline 

 essentially as in inner tooth but main axis lying at right angles 

 to tooth-row ; posterior surface of shaft broadly concave ; inner 

 margin with small though distinct secondary cusp ; cingulum 

 moderately well doveloped. The main cusps of the two teeth lie 

 in line of general curve of anterior portion of tooth-row. Space 

 between outer incisor and canine about equal to greatest diameter 

 of incisor. Lower incisors forming a continuous, broadly U -shaped 

 row between canines, their crowns very slightly imbricated ; 

 crowns much longer than high, trifid, that of i x narrowest, 

 longest and lowest, that of i 2 and i 3 widened posteriorly but 

 without additional cusps or tubercles. Upper canine robust, 

 the greatest diameter of its crown about three-quarters length 

 of anterior border of shaft, the cross section of shaft broadly 

 triangular with longest side formed by nearly flat postero-internal 

 surface ; a sharply defined antero-exteral longitudinal groove, and 

 less definite postero-external concavity ; anterior edge narrow 

 but not strictly trenchant ; posterior edge trenchant, with well 

 marked angle slightly below middle, this angle frequently becom- 

 ing a distinct secondary cusp ; cingulum well developed but not 



