1918 | Grinnell: A Synopsis of the Bats of Califorma 241 
southern California and Arizona, also in the Greater Antilles and the 
Bahama Islands. EHuwmops is found in the warmer parts of America 
north to the southwestern United States, and in the Greater Antilles. 
Euderma is the most closely restricted of our genera, having so far 
been found only in the southwestern United States. 
The genera of bats now occupying California may be inferred to 
have reached their present location from three different sources. 
First, cosmopolitan genera, namely Myotis, Eptesicus, Nyctinomus 
and Pipistrellus probably originated in the Old World. Second, 
Nycteris, Lasionycteris, Antrozous and Corynorhinus probably orig- 
inated in temperate North America. Third, Macrotus and Humops, 
southern genera, probably originated in tropical America and 
now reach their northernmost limit along the southern edge of our 
state. With the second group may be classed the genus Huderma, 
now confined to the extreme southwestern United States, and most 
closely related to the genera Corynorhinus and Plecotus, of the tem- 
perate zones. 
GEOGRAPHIC DISTRIBUTION OF Bats 
Bats occur throughout the eastern and western hemispheres to 
the northern and southern limits of tree growth (Miller, 1907, p. 43). 
Their day-time haunts vary from the cool, humid depths of mountain 
caves or tunnels to the torrid and arid rock-crannies of the desert. 
Their nocturnal foragings must involve extremes of temperature and 
humidity equally as great. When each species is considered sep- 
arately, however, we find it to be nearly, if not quite, as strictly 
limited in range as are other mammals, and this in spite of better 
powers of locomotion. 
It has been so generally supposed that bats show far less geo- 
eraphie variation than do other small mammals that the opinion of 
two recent workers in the order Chiroptera may properly be quoted 
here. One of these, Barrett-Hamilton (1910, p. 20), says: 
Neglect of bats is a grave error in studying geographical distribution, since, 
inasmuch as these creatures are possessed of the power of surmounting obstacles 
which to other mammals must be insuperable, their permanent restriction to definite 
regions must be due to causes of fundamental importance. And, whereas the 
wings of bats should have enabled them to occupy with uniformity the entire 
extent of the British Islands, we find in fact that their distribution therein is not 
less restricted than that of other mammals. 
