746 
EXPLANATION OF THE PLATES. 
PLATE XLV. 
Page. 
Fig. 1— SpermopMlm douglassi, Eich.—Oregon ground squirrel.—No. 1881.—Oregon 
Territory. 309 
a —skull from below ; h —skull from above ; c—skull from the side ; d — 
left side of lower jaw ; e —left side of lower jaw from above. 
Fig. 2 —Sciurus carolinensis, Grm.—Gray squirrel.—No. 1626.—Washington, D. C.... 256 
Keferences a-e as in fig. 1. 
Fig. 3— Sciurus douglassi, Bach.—No. 2229.*—Upper Des Chutes, Oregon Territory... 275 
Eeferences a-e as in fig. 1. 
Fig. 4— Tamias townsendii, Bach.—No. 2226.—Cape Flattery, Wash. Territory. 301 
Eeferences a-e as in fig. 1 ; /—left upper molars from helow ; g —left lower 
molars from above. These last two magnified nearly three diameters. 
Fig. 5— Spermophilus lateralis, Say.—Squirrel.—No. 2228.—Upper des Chutes, Oregon 
Territory... 312 
Figs, a-g; references as in the last figure. 
PLATE XLVI. 
Fig. 1— Sciurus liudsonius, Pallas.—Eed squirrel.—No. 727.—Carlisle, Penn. 260 
Skull a-e as in preceding plate. 
Fig. 2— Tamias striatus. —Ground squirrel.—No. 1898.—Essex county. New York.... 292 
a-g, as in fig. 4 of preceding plate ; f-g magnified two diameters. 
Fig. 3— SpermopTiilus heecheyi, Eich.—No. 1598.—Tejon valley. 307 
a-g as in preceding figure. 
Fig. 4— Spermophilus franhlini, Eich.— ? No. 1885.—Eacine, Wisconsin. 314 
a-e as in fig. 1. 
PLATE XLVII. 
Fig. 1— Arctomysfiaviventris,^di.c)a.. —Yellow-footed marmot.—No. 2372.—Black hills. 343 
Skull, a-e as in plate XLVI. 
Fig. 2— Cynomys ludovicianus, Eaf.—Prairie dog.—No. 1350.—Fort Kearney. 331 
a-e as in the preceding. 
Fig. 3— Cynomys ludovicianus, Eaf.—No. 1349. 331 
Molars of a very old individual, much worn obliquely; a —under view of 
right upper molars ; h —upper surface of lower molars. 
Fig. 4 —Cynomys gunnisonii, Bd.—No. 1636.—Cochetope Pass..... 335 
Eeferences a-g, as in fig. 4, plate XLV ; f-g slightly enlarged. 
PLATE XLVIII. 
Fig. 1— Castor canadensis, Kuhl.—Beaver.—No. 1003.—Eio Grande, Texas. 355 
Skull, reduced to two-thirds natural size ; a —skull from helow; h —skull 
from above; c—skull from, the side; d —left side of lower jaw ; e—left 
side of lower jaw from above. 
Incorrectly printed 2269 in the Hst of specimens. 
