746 EXPLANATION OF THE PLATES. 



PLATE XLV. 



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, Gm. 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. 4Tamias 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 XL VI. 



Fig. 1 Sciurus hudsonius, 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. Tej on valley 307 



a-g as in preceding figure. 

 Fig. 4 Spermophilus franklini, Rich. 9 No. 1885. Racine, Wisconsin 314 



a-e as in fig. 1. 



PLATE XLVII. 



Fig. 1 Arctomysjlaviventris, Bach. Yellow-footed marmot. No. 2372. Black hills. 343 



Skull, a-e as in plate XL VI. 

 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 XLV ; f-g slightly enlarged. 



PLATE XLV1II. 



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 

 aide of lower jaw from above. 



* Incorrectly printed 2269 in the list of specimens. 



