258 University of California Publications in Zoology [Vou.17 
Tn regard to the usual number of young, Stephens (1906, p. 277) 
says: ‘‘The young are born in June. More than half of the females 
bear two young, the remainder but one.’’ In the ease of the above 
described colony near Toro all the pregnant females examined con- 
tained but one foetus each. 
Family VESPERTILIONIDAE 
The distribution of this family is the same as that of the order 
Chiroptera. 
The members of this family include bats having muzzles without 
distinct leaflike outgrowths and having ears with well developed 
anterior basal lobes; the tragus is simple and usually well developed ; 
the tail is well developed, but extends only to, or but very slightly 
beyond, the edge of the wide interfemoral membrane. 
Miller (1907, p. 196) divides the family into six subfamilies, rep- 
resented by forty genera. The two subfamilies occurring in America 
north of southern Mexico are the Vespertilioninae and the Nyeto- 
philinae, and both are represented in California. 
Subfamily VESPERTILIONINAE 
Distribution same as for the Family. Primitive in structural 
features, being characterized chiefly by lack of specialized structures 
distinguishing the other subfamilies. Differs from the Nyetophilinae 
in the absence, in all of its members, of abrupt truncation of the 
muzzle, and of any ridge above the nostrils. 
Genus Myotis Kaup 
Representative species of this genus are found in the temperate 
and tropical regions of both hemispheres; the area of their distribution 
is probably not exceeded by that of any other genus of bats. About 
eighty species and subspecies of Myotis are now known, fifteen of 
which oceur in California. 
22 flak pi 3-3* moe 2 oe 
Say) dil? sea) a3) 
Upper incisors well developed, subequal, and closely crowded ; crowns 
almost cylindrical in cross-section; inner incisor with a distinet 
posterior secondary cusp, the outer with a well developed concave sur- 
face directed toward canine, from which it is separated by a space not 
Characters —Dental formula: 
*In at least one species, Myotis occultus, the upper middle premolar, pm*, is 
sometimes wanting. 
