1918] Grinnell: A Synopsis of the Bats of California 245 
NOMENCLATURE 
The nomenclature here used is for the most part that adopted by 
Miller (1912).. Where it has seemed necessary to deviate from this 
standard, an explanation is given in the account of the species con- 
cerned under the heading Synonymy and History. 
CLASSIFICATION 
All bats are included in the order Chiroptera and are in common 
distinguished by the following characters: 
Mammals with the front limbs modified for true flight, the fingers greatly 
elongated (the third usually at least equal to head and body) and joined together 
by a membrane which extends to sides of body and legs; shoulder girdle much 
more developed than pelvis, the sternum usually keeled; knee directed backward 
owing to rotation of leg for support of wing membrane (Miller, 1907, p. 43). 
The families of bats fall naturally into two main groups, the 
Megachiroptera and the Microchiroptera. The first of these groups, 
the Megachiroptera, or fruit-eating bats, represents an evolutionary 
stage much nearer to ordinary mammals than the latter. Its mem- 
bers are distinguished externally by the presence of a claw on the 
end of the second digit as well as on the pollex, by the completeness 
of the ring formed by the margin of the ear, and by the absence of a 
tragus. Andersen (1912, p. vi), the most recent worker on the group, 
recognizes 228 genera. These are confined to the tropical and sub- 
tropical regions of the Old World, east to Australia, Samoa, and the 
Caroline Islands. Hence none of them fall within the scope of the 
present paper. The second group, the Microchiroptera, comprises 
those bats characterized by the absence of a claw on the second digit, 
by the incompleteness of the ring formed by the margin of the ear, 
and by the presence, normally, of a tragus (Miller, 1907, p. 44). The 
same author (loc. cit., p. 78) recognizes six hundred genera which he 
has grouped into sixteen families. The Microchiroptera are found in 
both the eastern and western hemispheres. 
Only three of the families listed by Miller occur in the Western 
Hemisphere north of the Bahama Islands and Central Mexico. These 
are: the Phyllostomidae, represented in California by a single species; 
the Vespertilionidae, represented by twenty-six species and subspecies ; 
and the Molossidae, represented by four species. These bats may 
be identified with the aid of the appended keys, which are wholly 
artificial and make no pretense of indicating natural relationships. 
Anyone interested in the classification of the families and genera 
of bats by means of skeletal and dental characters is referred to 
Miller’s (1907) The Families and Genera of Bats. 
