THE FAMILIES AND GEKEKA OF BATS. 241 



is distinctly greater than their length. Canines well developed, not 

 peculiar in form, the lower approximated posteriorly, though not in 

 contact, the antero-inner edge with distinct convexity just above level 

 of incisors, the posterior base with small rounded, median cusp. 

 Upper premolars well developed, the anterior (pm 2 ) very slightly 

 smaller than posterior (pm 4 ) and closely approximating it in form, 

 the posterior tooth with distinct antero-internal cusp, lower premolars 

 large, the anterior (pm 2 ) not as high as posterior (pm J but fully 

 equal to it in cross section of base ; each tooth has a rounded postero- 

 basal cusp much like that of lower canine. Molars normal ; m * and 

 m * with inner segment deeply divided from outer, its inner border 

 squarely truncate, the protocone rather low but long, its commissure 

 abruptly bent downward posteriorly at a point corresponding to the 

 usual position of the hypocone when present, but with no other dis- 

 tinct trace of hypocone; a narrow but evident postero-internal heel 

 present in both teeth, but particularly well developed inm 1 ; third 

 upper molar with large metacone and third commissure ; lower molars 

 with all the cusps present and of the usual form, though rather low 

 and thick ; pm 3 with distinct entoconid. Skull in general appear- 

 ance not unlike that of Myotis myotis, but somewhat smaller, dis- 

 tinctly narrower, and with much shorter, almost uniformly convex 

 zygomata. Posterior opening of antorbital canal essentially as in 

 Natalus, occupying practically the entire anterior wall of orbit and 

 extending upward to and including region occupied in Myotis by the 

 lachrymal foramen which here does not exist as a separate orifice; 

 anterior opening of canal larger than in Myotis, but not extraordi- 

 narily so. Foramen rotundum very large, coalesced with optic fora- 

 men, the aperture broadest and squarely truncate anteriorly, where 

 breadth is about equal to that of interptergoid space. Palate slightly 

 concave both laterally and antero-posteriorly, the anterior portion 

 entire except for two minute lateral foramina; pterygoids parallel. 

 Basiphenoid pits barely indicated. Audital bullae essentially as in 

 Myotis myotis, but not as large. Mandible differing conspicuously 

 from that of Myotis in the low coronoid (not exceeding articular 

 process in height) and short angular process. 

 Species examined. — Mystaeops tuberculatus (Gray). 



Family MOLOSSID^E. 



3821. Noctilionidm (part; Race 1, part) Gray, London Medical Repository, 

 XV, p. 299, April, 1821. 



1827. Vespertilionina Lesson, Man. de Mammalogie, p. 99 (part). 



1831. Vespertiliones (Vespertilionida') (part: Noctilionina, part) Bona- 

 parte, Saggio di una distrib. metodica degli Anim. Vert., p. 14. 



1838. Vespertilionidce (part; Noctilionina, part) Bonaparte, Nuovi Annali 

 delle Scienze Naturali, Bologna, Anno I, Tomo II, p- 112, • 



25733— No. 57—07 m 16 



