334 bulletin: museum of comparative zoology. 



of Milwaukee, Prof. Z. P. Metcalf of the North CaroHna College of 

 Agriculture, Prof. F. Payne of Indiana University, and Mr. M. L. 

 Church of Marshall, N. C. 



Generic Affinities. 



The Big-eared Bats of the genus Corynorhinus take the place of the 

 Old World vespertilionine genus Plecotus in North America. In 

 essential characters the two genera are very similar, and are evidently 

 closely related. Miller (1907, p. 225) in his " Families and Genera of 

 Bats" considers that "the great development of the glandular masses 

 on muzzle, and the absence of the distinct lachrymal ridge, distinguish 

 this genus sufficiently from Plecotus," to which LeConte and con- 

 temporary writers at first referred specimens. The shape of the 

 nostrils is also diagnostic, but the presence of a distinct lachrymal 

 ridge in a new species from Mexico (see p. 352), invalidates that charac- 

 ter as distinctive of Plecotus. In 1864, Harrison Allen used Synotus 

 of Keyserling and Blasius for the American bat, but in the following 

 year he erected for it the new genus Corynorhinus, by which it con- 

 tinues to be known, although Dobson in his Catalogue of Chiroptera 

 in the British Museum (1878) took the more conservative course of 

 regarding it as a subgenus of Plecotus. The dental formula — i 3^ 

 c Pi, 'ptn 3Z3, wi 333 = 36 — is the same in both genera and shows 

 but slight numerical reduction over that of Myotis, in the presence of 

 two in place of three upper premolars on each side. In view of this 

 somewhat primitive or unreduced tooth formula it is perhaps less 

 surprising to find among the many specimens examined a single one 

 with three upper incisors. This condition is perhaps to be considered 

 reversionary to the more primitive state in which the full number of 

 three upper incisors characteristic of placental mammals, is present. 

 It has been generally assumed that it is the innermost upper incisor 

 that was the first to be lost in all bats with two incisors, partly be- 

 cause of the " correspondence of the two upper teeth with th' two outer 

 of the lower jaw when the maximum set is present, and also, even more 

 strongly, by the general tendency throughoiit the group for the pre- 

 maxillaries to become reduced, particularly along the inner edge" 

 which would "inevitably result in eliminating that part of the bone 

 in which the first incisor grows" (Miller, 1907, p. 27). Andersen 

 (1912, p. xxiv) without going further into the matter, asserts, however. 



