171 



parietal. Ventral profile rising slightly but evidently in region 

 of floor of brain-case. Greatest depth of brain-case about three- 

 quarters mastoid width ; sagittal and lambdoid crests slightly 

 indicated in fully adult individuals. Interorbital region obscurely 

 short hour-glass shaped. Anteorbital foramen small, its posterior 

 border over posterior root of large premolar. Posterior palatal 

 region rather narrow, its width immediately behind molars about 

 equal to its greatest length, the median spine broad and short ; 

 mesopterygoid fossa slightly wider than long, the hamulars turned 

 inward. Auditory bulla moderate, its greatest diameter nearly 

 equal to distance between inner margins of bullse. 



Teeth. — Upper incisors sub-equal, about half as high as canine, 

 each pair in contact or nearly so at base but diverging at tips, the 

 cingulum of inner tooth horizontal, that of outer tooth oblique ; 

 crown of outer incisor squarish in cross section, that of inner 

 somewhat elongated in axis of tooth-row ; near point of contact 

 each shaft bears a secondary cusp, this usually though not always 

 better developed in outer than in inner tooth ; distance between 

 canine and outer incisor about equal to diameter of incisor, that 

 between pairs a little more than 

 twice as great. Lower incisors 

 slightly but evidently imbricated, 

 forming a continuous, broadly 

 V-shaped row between 

 canines ; crown of i 3 sub- 

 terete, its area more than 

 half that of canine and 

 about equal to that of pm v 

 its blunt main cusp, the 

 highest in the incisor series, 

 situated at outer side, the 

 three smaller cusps (third 

 obsolete) on inner margin ; 

 i x and i 2 sub-equal, slightly 

 lower than i 3 , their crowns 

 compressed, longer than 

 high, trifid, that of second 

 wider posteriorly than an- 

 teriorly, and usually with 

 a minute postero-internal 

 cusp. Upper canine rela- 

 tively large, slightly higher than main cusp of large premolar, 

 its shaft somewhat triangular in cross section, with broad 

 postero-internal concavity and anterior and postero-external 

 groove ; posterior cutting edge well developed ; cingulum com- 

 plete but not forming evident secondary cusps. Lower canine 

 lower and less acutely pointed than upper, its tip about on level 

 with highest cusps of molars ; cingulum usually forming a slight 

 secondary cusp anteriorly. First and second upper premolars 



FIS. 80. 

 Myotis mystacinus. Teeth X 10. 



