BPTBSICUS 



229 



quarter that of canine, the subterete shaft directed inward and 

 slightly forward, its secondary cusp large and prominent, situated 

 on outer side of shaft near tip ; cingulum well developed, but 

 without cusps. Outer upper incisor much shorter than inner 

 and with about half its crown area, the apex of its shaft slightly 

 exceeding level of cingulum of larger tooth ; outer and posterior 

 surfaces flattened or double-concave, tbe two concavities some- 

 times separated by a low but evident ridge ; inner margin with 

 a low secondary cusp on well developed cingulum. A line 

 perpendicular to main axis of skull would pass through centre 

 of shafts of all four incisors ; the outer tooth is separated from 

 canine by a space about equal to breadth of its own crown. Lower 

 incisors large, much crowded, and very conspicuously imbricated, 

 i 1 and i 2 overlapping more than half of front surface of the 

 succeeding tooth, the general outline of the entire series V-shaped ; 

 front surface of crowns about as high as wide, the edge obliquely 

 trifid (occasionally a low, rudimentary fourth cusp at outer 

 margin of i 2 ) ; cross section of crown somewhat triangular, the 

 posterior angle occupied by a low tubercle in i 2 and i 3 . Upper 

 canine large, its shaft decidedly the highest of the upper series, 

 its cross section sub-triangular, the posterior cutting edge well 

 developed, the anterior less trenchant than in Nyctalus noctula ; 

 inner surface divided by a low ridge into two shallow con- 

 cavities, the posterior of which is the larger ; antero-outer surface 

 convex ; postero-outer surface with deep longitudinal groove ; 

 cingulum narrow but complete, without cusps. Lower canine 

 very robust, the diameter of crown noticeably greater than least 

 distance between canines, the shaft decidedly higher than main 

 cusps of molars, smoothly rounded in front, flattened-concave 

 behind and on inner side, the cingulum narrow but complete 

 except at point of contact with i 3 , where it becomes abruptly 

 obsolete, terminating in a slight tubercle corresponding to the 

 cusp present in Nyctalus and Pipistrellus. Upper premolar with 

 crown area about equal to that of canine and about two-thirds 

 that of first molar, its main cusp robust, nearly as long as canine 

 (measured along cingulum), sharply trenchant posteriorly, flat- 

 tened-concave on inner side, a well developed external and antero- 

 internal longitudinal groove ; crown with slight anterior and 

 more marked posterior emargination, the inner side narrow, with 

 slight concave crushing surface and well developed cingulum, 

 which rises to a small cusp anteriorly. Lower premolars closely 

 crowded, the crown area of first about half that of canine, that 

 of second nearly four-fifths that of canine ; cusp of first a little 

 more than half as high as second, which slightly exceeds main 

 cusps of molars ; cingulum of each tooth well developed, tending 

 to form a slight postero-internal tubercle. First and second 

 upper molars sub-equal in crown area, the second wider but more 

 constricted at middle ; protocone robust, not very high ; no true 

 hypocone, but region which it would occupy indicated by slight 



