SCIURID^ 63 



of the world except Australia, and are well represented in Cali- 

 fornia. The larger species are hunted for their flesh. Many 

 species are destructive of crops. 



The food is principally the seeds, fruits, tubers, roots, leaves 

 or stems of many kinds of plants, shrubs, and trees. Many 

 species eat more or less insects and a few eat flesh occasionally. 

 Most species are strictly diurnal, but the Flying Squirrels are 

 principally nocturnal. Some species are arboreal, some are ter- 

 restrial and many are fossorial. 



The sexes are alike. The young differ but little from adults. 

 In many species there are considerable seasonal changes of pelage, 

 and a number of species are dichromatic, but dichromatism does 

 not appear to occur in any Californian species. There are us- 

 ually foiir pairs of mammae, occasionally five. The number of 

 young in a litter varies greatly, rarely as few as one or two, fre- 

 quently six or eight, rarely ten. 



Genus Marmota Frisch. (Marmot.) 

 Skull very short, broad posteriorly, narrow and flattened 

 between the orbits ; anteorbital foramen rather large, oval or pear 

 shaped; postorbital processes long; penutimate premolar com- 

 paratively large; small internal cheek pouches; ears rather short; 

 tail rather broad, about one third as long as head and body ; inner 

 toe on front foot rudimentary, with a flat nail ; habit fossorial : 

 mamma ten ; pelage coarse ; size very large for the family. 



Dental formula I, i — i ; C, o — o; P, 2 — i ; M, 3 — 3X2=22. 



Marmota flaviventer Aud. and Bach. (Yellow^ — belly.) 



YELLOW-BELLIED MARMOT. 



Above grizzled brown, the hairs being whitish at tip, with 

 a broad pale chestnut zone and pale drab base; forehead, chin 

 and lips dull white; nose sepia; top of head dark sepia; sides of 

 neck buff; fore legs, hind feet and under surface of body vary- 

 ing from yellowish brown or wood brown to burnt umber; tail 

 russet or cinnamon rufous on both surfaces. 



