﻿58 



NORTH AMERICAN FAUNA. 



but truncate posteriorly and slightly longer than broad. Forehead 

 moderately elevated above muzzle j occiput high and compressed, with 

 well-developed ridges. Distance from posterior border of last upper 

 molar to tip of hamular equal to or less than distance between alveoli 

 of posterior molars. 



Teeih. — Upper incisiors diverging at tips, tbe inner tooth of each pair 

 much the larger. First and second premolars in the tooth row or 

 second displaced slightly inward and partly concealed by the anterior 

 edge of the third, the relative size of the two teeth variable, but first 

 always the larger. The second premolar is always much shorter than 

 the first, but the cross section of the crown is sometimes nearly equal 

 in the two teeth. On the other hand, in rare cases the area of cross sec- 

 tion in the first is nearly double that of the second. Third upper pre- 

 molar triangular in outline, posterior margin longest, the outer margin 

 abruptly convex anteriorly, the anterior and posterior borders slightly 

 concave; inner apex of triangle bluntly rounded and not reaching to 

 level of inner margins of molars. Crowns of first and second upi)er 

 molars trapeziform in outline, the anterior edge longest, and the poste- 

 rior, outer, and inner edges successively shorter. Anterior edge slightly 

 convex, posterior edge slightly concave. Crown of first molar consid- 

 erably shorter in x^roportion to its width than second (fig. 14 r7, p. 6L). 

 Inner mandibular incisors smallest, their crowns compressed and trifid; 

 middle incisors similar but larger; outer incisors about as large as the 

 two others together, their crowns irregularly terete, and with four indis- 

 tinctly developed tubercles, one of which is much larger than the others. 

 First and second i^remolars perfectly in line, the first considerably larger 

 than the second, though not much wider in cross section. Third pre- 

 molar as broad as long, trapeziform, the posterior margin longest. 



Measurements. — In the following table average measurements are 

 given of 20 specimens of Myotis velifer from six localities. 



Average measurements of 20 specimens of Mi/otis velifer from 6 localities. 



Locality. 



Michoacari: Patzcuaro 



Hidalgo: Tnlancingo 



Mexico: Ixtapalapa 



Arizona : San Bernardino Eaiicli 



Texas : San Antonio 



San Antonio 



^lissouri : Marble Cave 



iType of 'incautus.^ 



5 



99 



44.8 



18.5 



3 



97 



42 



18.3 



IcT 



94 



40 



17.6 



4 



98.8 



42 



16.5 



11 



95.2 



44.4 



18 



4 



93.3 



41.3 



18.1 



3 



93.6 



39.6 



17.9 



9.5 

 8.9 

 8.6 

 9 



8.4 

 9.3 



45 



43.6 



42 



41.5 



43 



43 



42.6 



7.2 

 7.2 

 6.4 

 6.4 

 7 



73.4 



71.3 



71 



69 



62 



16 



16.1 



15.4 



10.6 

 10.3 



n 



15.6 10.1 



.8.5 

 9 



7.8 



8.1 



