126 BULLETIN 57, UNITED STATES NATIONAL MUSEUM. 
Genus OTOPTERUS Lydekker. 
1843. M acrotus Gray, Proc. Zool. Soc., London, p. 21. Not Macrotis Reid, 
1837. 
1878. M acrotus Dobson, Catal. Chiropt. Brit. Mus., p. 463. 
1891. Otopterus Lydekker, in Flower and Lydekker, Mammals, living and 
extinct, p. 673. 
1904. Macrotus H. Allen, Monogr. Bats N. Amer., 1893, p. 33, March 14, 
1894. 
1904. Macrotus Miller, Proc. U. S. National Museum, XXVII, p. 345, 
January 23, 1904. 
1904. Macrotus Rehn, Proc. Acad. Nat. Sci. Philadelphia, p. 427, April, 
1904, issued June 29, 1904. 
Type-species. — Macrotus waterhousii Gray. 
Geographic distribution. — Warmer parts of middle America from 
Guatemala to southern California and Arizona, also the Greater 
Antilles and the Bahama Islands. 
Number of forms. — Eight forms are recognized by Rehn, the most 
recent writer on the genus. 
Characters. — Dental formula and structure of teeth, essentially as 
in Micronycteris , but first and second upper molars without hypo- 
cones, and entoconid of first and second lower molars not as well 
developed ; paraconid of m x about as in Micronycteris or slightly 
more reduced. Skull like that of Micronycteris except that the 
brain case rises less abruptly in front, forming only a very slight 
angle with rostrum, the rostrum is distinctly flattened above, and the 
audital bullae are conspicuously enlarged, covering almost the entire 
cochleae, their greatest diameter distinctly greater than the width of 
the space between them; basisplienoid pits even less distinct than in 
Micronycteris. Externally distinguishable from Micronycteris by 
the even larger ears and by the much longer tail, the extremity of 
which projects beyond the hinder edge of the broad inter femoral 
membrane. 
Species examined . — With the exception of Otopterus pygmceus I 
have examined all the known forms of this genus. 
Remarks . — Although there seems to be no good reason for reject- 
ing the name Macrotus of Gray on account of the previous use of 
the same word by Leach as a nomen nudum applied to the long-eared 
bat of Europe, or on account of De jean’s Macrotis , 1833, the case is 
different as regards Reid’s Macrotis of 1837. This name is properly 
defined and is clearly of the same etymology as Gray’s Macrotus. 
1 therefore prefer to adopt Otopterus. 
