746 
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EXPLANATION OF THE PLATES. 
PLATE XLV. 
1—Spermophilus douglassi, Rich.—Oregon ground squirrel.—No. 1881.—Oregon 
MOLTO. st avddas de -chadsids Savapilaenecobnemwstedte tense nt of sc oeebe'dute Sepaltgnanss «iaases 
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. 
2—Sciurus carolinensis, Gm.—Gray squirrel.—No. 1626.—Washington, D. C.... 
References a—e as in fig. 1. 
3—Sciurus douglassi, Bach.—No. 2229.*—Upper Des Chutes, Oregon Territory... 
References a—e as in fig. 1. 
4—Tamias townsendii, Bach.—No. 2226.—Cape Flattery, Wash. Territory....... 
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. 
5—Spermophilus lateralis, Say.—Squirrel.—No. 2228.—Upper des Chutes, Oregon 
IDeriitory,.< wosislasseesanieemeenens danepratesnie saaseocd se eee wavees annonce: ae adaasdsseles 
Figs. a-g; references as in the last figure. 
PLATE XLVI. 
1—Sciurus hudsonius, Pallas.—Red squirrel.—No. 727.—Carlisle, Penn.......... aa 
Skull a-e as in preceding plate. 
2—Tamias striatus. —Ground squirrel.—No. 1898.—Essex county, New York.... 
a-g, as in fig. 4 of preceding plate ; f-g magnified two diameters, 
3—Spermophilus beecheyi, Rich.—No. 1598.—Tejon valley.......11ssseeseceeeseees apnoS 
a-g as in preceding figure. 
4—Spermophilus franklini, Rich.— 9 No. 1885.—Racine, Wisconsin.............00008 
a-e as in fig. 1. 
PLATE XLVI. 
1—Arctomys flaviventris, Bach.—Yellow-footed marmot.—No. 2372.—Black hills. 
Skull, a-e as in plate XLVI. 
2—Cynomys ludovicianus, Raf.—Prairie dog.—No. 1350.—Fort Kearney.......... : 
a—e as in the preceding. 
3—Cynomys ludovignanua, Rat.—No, 1349,,,...sssysrsssnncssssceccccssecececsscedsecenneosens 
Molars of a very old individual, much worn obliquely ; a—under view of 
right upper molars ; /—upper surface of lower molars. 
4—Oynomys gunnisonii, Bd.—No. 1636.—Cochetope Pass.......sscccecseeseseeeseeeeseee 
References a-g, as in fig. 4, plate XLV; fg slightly enlarged. 
PLATE XLVIII,. 
1—Castor canadensis, Kuhl.—Beaver.—No. 1003,—Rio Grande, Texas..........+ : 
Skull, reduced to two-thirds natural size; a—skull from below; 6—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 st of specimens. 
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