MUniD.Tl-AUVlCOLIN.K— AUVI(X)riA uii'Aim;s. 



157 



Jrrico/fl n/ftoni/(wcn«, Kmmons, Ucp. Qmul. Mn8H. ISIO, (iO (MnssncliiiBcltH; |initiiil iilbimi)— 1'kKav, N. 



Y. Zool. i, lH4"i, H',1 (HiiniP as KmiiiniiK's). 

 Arrimla Urmlm, Emmons, Rc|i. Quad. Miis.-t. IHId, (>0.— DkKav, N. Y. I'li. i, 1H48, HIi (snme nn Eiiinioiin'H). 

 Jrna)Iaiia«H(<i, IIaciiman,, luiiin. Acad. Nut. irici.l'liilii.viii.pt.ii, 1H4'.>. ■^,K;(Miu<8Hi'liuiiL<ttN). — Ari>. & IIacii., 



Q. N. A. iii, 185;i, 211, pi. clxiv, f. 2 (Mn88.icliH«etts, N<nv York, niiil Miclii({nn).— LkContk, 



Proc. Acad. Nat. Sci. Pbila. vi, 1H53, 4U7 (iiiiotcs " Wii'gDinim'H AreLiv, I84:<, !>2, and Scbiuz, 



251 "). 

 Arvkota Oiieida, DkKav, N. Y. Zool. i, 1842, 88, pi. xxiv, f. 1 (youiiR ; Now York).— LkContk, Proc. Acad. 



Nut. Sci. Pljila. viii, 1853, 400 (same 08 DcKuj'n). 

 /JiTirafo rufmceng, DkKay, N. Y. Zool. i, 1842, 85, pi. xxii, f. 1 (Nortliern New York). 

 Anicota ocdden(o/i», Pkai.e, Mainni. U. 8. Expl. Exped. 1848, 45 (Piiget's Sound).— LkCdste, Proc. Acud. 



Not. Sci. Pbilo. vi, 185:1, 408 (miiub as PcoIoV).— Ai,l>. & Bach., Q. N. A. iii, 1854, 2U4 (auine 



08 Pcale's).— Baird, M. N. A. 1W)7, 5:14 (Peale's type described), 

 Anicola cali/ornica, Pk.vle, Momm. U. S. Expl. Exped. 1848, 40 (Coliforniu).— LkContk, Proc. Acail. Nut. 



Sci. Pbila. vi, 185:1, 408 (same as Pcalc's).— Aid. & Bach., Q. N. A. iii, 18.54, i!93 (someoa 



Peale's).- BAlim, M. N. A. 1857, 532 (Peale's type). 

 Artlcola montana, Pkale, Mainm. U. S. Expl. Exped. 1848, 44 (Mount Sbasta, Cal.).— Aim. & Bach., Q. 



N. A. iii, 1854, :i02 (same as Peale's).- Baird, M. N. A. 1857, 528 (California and t Nebraska). - 



NEWUEKitv, P. U. K. Kep. vi, 1857, Zool. 61. 

 Arricola edax, LeConte, Proc. Acad. Not. Sci. Pbila. vi, 1653, 405 (California).- Aui>. & Bach., Q. N. A. 



1854, iii, 270, pi. 154, f. 2 (taken from LeConte's type, and description compiled from 



LeConte).— Baihd, M. N. A. 1857, .531 (description from LeConte's tyiMs). 

 Arricola borealia, LeConte, Proc. Acnd. Nat. Sci. Pbila. vi, 18.53, 407, excl. syiion. (not of Ricbardson, &e. 



Tlie species is based upon specimens from Rbodo Island now in Mus. Smitbs.). 

 Artsicola trotciridgti, Baird, M. N. A. 1857, .529, in text (name suggested from some supposed dental pecul- 

 iarities of No. -fiW, Mus. Smiths., from Monterey, Cal.). 

 inicola longiroalris, Baird, M. N. A. 1857, .5:10 (based on supposed cranial peculiarities of No. HH, Mns. 



Smitbs., from California).— Newberry, P. U. K. Rep. vi, 18,57, Zool. 01. 

 Anicola modetta, Baird, M. N. A. 1857, .535 (based on No. VV'it, from Kocky Mountains; very young). 

 Arvicola riifidorsum, Baird, M. N. A. 18.57, 520 (Holmes' Hole, Mnss. ; a very red specimen). 

 Arvicola brcweri, Baird, M. N. A. 1857, 525 (bleached breed from Miiskeget Island, Mass.). 



Skull. — The cranium of Arvicola riparius bus not a single specifically 

 diagnostic feature ; all its characters are subgeneric, shared by xanthognalkuit, 

 and by the various geographical strains more or less deviating in external liiar- 

 acters from ordinary riparius of the United Slates. It averages, of course, 

 smaller than that of xanthognalhus or even of var. totcnsendi ; but the mini- 

 mum of l)oth of these is within the average of riparius. Our table of meas- 

 urements indicates both size and shape so perfectly that those points need not 

 detain us here. The skull is not satisfactorily distingui.jhable, dentition aside, 

 from that of Pedomys; for the difference in the length of the nasal branches 

 of the intermaxillaries, given by Baird, does not always hold. From Fitymys, 

 it may generally be known (dentition aside) by being larger and not quite so 

 wide for its len;jth (as 0.59 to 1.00, instead of 0.62 to 1.00, as in Pitymys). 

 It averages much larger than that of Cliilotus oregoni. 

 . The dentition, likewise, offers nothing specifically diagnostic; all the 

 speci' and varieties of the subgenus having the same pattern of tlie molar 

 crowns. The present opportunity, however, is taken to fully describe tiie 



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