96 PROCEEDINGS OF THE NATIONAL MUSEUM vol. ho 



sort with long Ears, and particularly long stragling hairs. The other 

 much like the English, something larger I think, very common." 



There is now an extensive American literature on Euderma and 

 Plecotus, but most reports contain little more than records of speci- 

 mens. The only revisionary works have been those of H. Allen (1864, 

 1894), Miller (1897), and G. Allen (1916). Most of our knowledge 

 of the anatomy and physiology of the gi"Oup is included in the papers 

 of Larsell and Dow (1935) and Pearson, Koford, and Pearson (1952). 

 The few life history studies are generally superficial; those of Dalquest 

 (1947), Pearson, et al. (1952), and Twente (1955) are notable excep- 

 tions. Much yet remains to be learned about Euderma and the Ameri- 

 can populations of Plecotus. 



These bats occur in most temperate portions of the Northern 

 Hemisphere. They are generally scarce. In America, Euderma is 

 known by 16 specimens, the subgenus Idionyeteris is known by less 

 than a dozen specimens, all but two of them collected since 1955; and 

 perhaps no other North American bat with such an extensive geo- 

 graphic range as the subgenus Corynorhinus has been collected so in- 

 frequently. Species of the latter subgenus are known to occur from 

 the Atlantic to the Pacific and from Canada to the Isthmus of Tehuan- 

 tepec in Mexico. This wide geographic range is deceptive, however, 

 for these bats display narrow limits of tolerance in their choice of 

 habitat. Within the bounds of their ranges are large areas in which 

 they apparently do not occur, and others in which they occur only 

 sparingly. There are few areas in which they are common. 



Materials 



The scarcity of Euderma and Plecotus in America is evident from 

 the small number of museum specimens listed in the early reviews. 

 H. Allen's 1864 monograph included only 18 specimens, and his 1894 

 monograph only 19. For Miller's 1897 revision, 43 examples were 

 available. G. Allen's 1916 review was based on a total of 126 speci- 

 mens. 



The material from which I have drawn my conclusions concerning 

 these bats consists of four dry skins and skulls and a single specimen 

 preserved in alcohol representing Euderma; three specimens of the 

 subgenus Idionyeteris, dry skins and skulls; 25 dry skins and skulls, 

 two skeletons, and 32 specimens preserved in alcohol, representing at 

 least five races of the subgenus Plecotus; and about 800 specimens (see 

 species accounts for type of preservation) representing all the named 

 forms of the subgenus Corynorhinus. 



In the course of the study I have examined enough specimens to 

 define Euderma and American Plecotus, but have not attempted to 

 assemble aU available specimens. Those examined are in the collec- 

 tions of the following: 



