746 
EXPLANATION OF THE PLATES. 
PLATE XLY. 
Page. 
Fig. 1 —Spermophilus douglassi, Rich.—Oregon ground squirrel.—No. 1881.—Oregon 
Territory. 309 
a —skull from below ; b —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, Grin.—Gray squirrel.—No. 1626.—Washington, D. C.... 256 
References a-e as in fig. 1. 
Fig. 3 —Sciurus douglassi, Bach.—No. 2229.*—Upper Des Chutes, Oregon Territory... 275 
References a-e as in fig. 1. 
Fig. 4 —Tamias townsendii, Bach.—No. 2226.—Cape Flattery, Wash. Territory. 301 
References a-e as in fig. 1 ; /—left upper molars from below ; 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 XLYI. 
Fig. 1 —Sciurus Tiudsonius, Pallas.—-Red 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 —Spermophilus beecheyi, Rich.—No. 1598.—Tejon valley. 307 
a-g as in preceding figure. 
Fig. 4 —Spermophilus franldini, Rich.— ? No. 1885.—Racine, Wisconsin. 314 
a-e as in fig. 1. 
PLATE XLYII. 
Fig. 1— Arctomysfiaviventris, Bach.—Yellow-footed marmot.—No. 2372.—Black hills. 343 
Skull, a-e as in plate XLYI. 
Fig. 2 —Cynomys ludovicianus, Raf.—Prairie dog.—No. 1350.—Fort Kearney. 331 
a-e as in the preceding. 
Fig. 3 —Cynomys ludovicianus, Raf.—No. 1349. 331 
Molars of a very old individual, much worn obliquely; a —under view of 
right upper molars ; b —upper surface of lower molars. 
Fig. 4 —Cynomys gunnisonii, Bd.—No. 1636.—Cochetope Pass. 335 
References a-g, as in fig. 4, plate XLY ; f-g slightly enlarged. 
PLATE XLYIII. 
Fig. 1 —Castor canadensis, Kuhl.—Beaver.—No. 1003.—Rio Grande, Texas. 355 
Skull, reduced to two-thirds natural size ; a —skull from below ; b —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 list of specimens. 
