200 BULLETIN 51, UNITED STATES NATIONAL MUSEUM. 
Upper incisors 1-1. 
Ears noticeably enlarged ; audital bullae much wider than space 
between them Otonycteris, p. 215. 
Ears not noticeably enlarged ; audital bullae not as wide as 
space between them. 
First and second upper molars with mesostyle reduced, the 
W pattern distorted or nearly absent ; first and second 
lower molars with second triangle smaller than first. 
Pachyotus, p. 219. 
First and second upper molars with normal cusps and 
ridges, the W pattern not distorted ; first and second 
lower molars with second triangle larger than first. 
Skull short and deep, the depth of braincase, including 
audital bulla, about one-half greatest length; meta- 
carpal of 3d, 4th, and 5tli fingers successively much 
shortened Dasypterus , p. 222. 
Skull normal, the depth of braincase, including audital 
bulla, considerably less than one-lialf greatest 
length ; metacarpal of 3d, 4th, and 5th fingers about 
equal in length. 
Third lower incisor noticeably smaller than first 
or second. 
Crown of third lower incisor in line with 
crowns of first and second, the tooth func- 
tional Rhogeessa, p. 218. 
Crown of third lower incisor scarcely visible 
under cingulum of canine, the tooth func- 
tionless Bceodon, p. 218. 
Third lower incisor as large as first or second. 
Third upper molar with well-developed meso- 
style, metacone, and three commissures. 
Lachrymal breadth greater than alveolar 
breadth Scotoecus, p. 217. 
Lachrymal breadth less than alveolar 
breadth Nyciiceius, p. 216. 
Third upper molar with mesostyle rudimen- 
tary or absent, and metacone very minute ; 
only two distinct commissures present. 
Depth of maxillary emargination equal 
to distance between canines. 
Scoteinus, p. 217. 
Depth of maxillary emargination scarcely 
more than one-half distance between 
canines Scotomcmes, p. 217. 
Genus MYOTIS Kaup. 
1829. Myotus Kaup, Skizzirte Entw.-Gesch. u. Natiirl. Syst. d. Europ. 
Thierw., I, p. 106 ( myotis ). 
1829. Nystactes Kaup, Skizzirte Entw.-Gesch. u. Natiirl. Syst. d. Europ. 
Thierw., I, p. 108 ( leisleri ). Not Nystactes Gloger, 1827. 
1830. Leuconoe Boie, Isis, p. 256. (Die Wasserfledermause. ) 
1839. Vespertilio Keyserling and Blasius, Wiegmann’s Archiv fur Natur- 
gesch., I, p. 306 (not of Linnaeus, 1758). 
