195 



about on level with main portion of brain-case, and very slightly 

 overhanging foramen magnum ; ventral profile scarcely elevated 

 posteriorly ; palate rather narrow (essentially as in M. mystacinns) ; 

 width of posterior extension of palate less than its length, median 

 spine short but well developed ; posterior border of anteorbital 

 foramen over anterior root of first molar ; mandible with coronoid 

 process relatively higher and narrower than in the small species, 

 its posterior border much more oblique. 



Teeth. — The dentition is of a less primitive type than in the 

 small European species of Myotis. This is indicated by the 

 general tendency to reduction shown especially in the lower 

 incisors, the small premolars and the posterior lower molar. 

 Upper incisors rather high and slender but not essentially 

 different in form fi'om those of M. mystacinus, the cingulum of 

 inner tooth obsolete, that of outer slightly developed. Lower 

 incisors very strongly im- 

 bricated, the outline of the 

 row U-shaped or broadly 

 V-shaped ; cutting edge of 

 «\ and ir^ trifid, but decidedly 

 oblique owing to reduction 

 in size of outer cusp ; a 

 minute cingulum cusp usu- 

 ally present at extreme outer 

 edge ; i^ with small postero- 

 internal tubercle ; i^ sub- 

 terete, 4-tuberculate, the me- 

 dian outer tubercle largest. 

 Canines relatively smaller 

 than in M. mystacinns and 

 with less developed posterior 

 cutting edge, their form 

 essentially as in M. nattereri 

 and M. einarginatus. Small 

 upper premolars much 

 crowded, the second usually 

 forced inward from line of tooth-row, sometimes so much so that 

 the first is practically in contact with large premolar. In form 

 they show no special peculiarities ; shaft subterete ; cingulum 

 well developed. Large upper premolar more reduced than in the 

 small species, the inner margin of crow^n a mere cingulum at base 

 of main cusp, and without trace of secondary cusps. Lower 

 premolars not peculiar in form, but middle tooth usually more 

 crowded between first and third than in the small members 

 of the group. Molars showing no special peculiarities of form ; 

 thickening that represents hypocone in m^ and m^ barely 

 indicated ; m^ more reduced than in the small species, its meta- 

 cone scarcely more than a slight widening of terminal portion of 

 third commissure. First and second lower molars essentially as 



o 2 



Fig. 33. 

 Myotis mrjotis. Teetli x 10. 



