MURIDiB— AUVICOLIN^— AKVICOLA. 



149 



produces a tooth that looks radically difFcrcnt in sculptiirn. The front lower 

 molar carries the same general plan of oppositeness instead of alternation of 

 the lateral triangles, which, with the distinctly double condition of the 

 indentatcd angles of enamel, where these meet along the middle, tends to 

 throw, and almost succeeds in throwing, the lateral triangles tiiat occur in 

 Arpkola into larger triangles, reaching quite across the toolh. Thus, fntin 

 behind forward, there is first one perfect triangular loop reaching across the 

 tooth; next, there are an external and an internal angle opposite eacli other, 

 inclosing a lozenge that reaches across the tooth; next, there are an internal 

 and an external angle, not quite opposite each other, and therefore forming 

 two nearly separated lateral triangles, generally not completely closed in, 

 liowevcr, but more or less continuous with Uic area of the large anterior 

 trefoil that finishes the tooth in front. 



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Genus AllVICOLA, Lact'pfcde. 



<J/iu, LiNNiEUS, Synt. Nnt. i, I76li, and niont early Authors. i 'i 



<Af»re> cuHJcutarii, Pallah, N. Sp. Glirium, 1776, 77. 

 <LemmHt, LiNCK ; Fikciikr, et al. 

 ityodn, Pallas, Ziiog. R.-A. i, ISII, 172. Nut Mi/oda of Selys-LoDgcLampH, 183U, wliicb =^ Hi/piidceut, 

 Keyserliug and Biasing, 

 <"AnU)ola, LACfei'^DK, Tableau, 1803" (fldo Agoaaiz), and most late authors. Includes amphibiHs and 



arvalu. 

 Klljipuiaut, Iluorr, Prod. 1811. Not of Koyserling and Blasius, nor of Daird. Includes Mu» lemmua, 

 ' ampkUAM, and arvalia. 



> Jlfynomea, Raklsesquk, Am. Monthly Mag. ii, 1817, 45. Type, If. pratenm — Wilson's Meodow-monse, 



=^ Anicola penntjiliianica On\. 



> rmmmomyt, LeContk, Ann. Lye. Nat. Hist. N. Y. 1829, 1:1:2 {pinetorum). Not of Rucppel. 



> rUyniyit, McMuRTniB, Am. od. Cuv. R. A. i, 1*11, 434. Typo, A. pinetorum, LeC. 



> Hemiolomyi, Sblys-Lonociiamfs, fitudos do Microm. 1839 85 (iucludus amphibiut, terratrit, &o.). 



> ^i«ra(iM, 8KLY8-LONOCIIA.MP8, op. cit. 1839, 8S. 



>/'ii««iHj», Lesson, NouT. Tab. R. A. 1848, 13 (pinctoriim). ' ' ''■ • 



> /femiotom^a, Daird, M. N. A. 1857, 515. Type, ^rvico'a ri;iariu< Ord. 



> Pedomi/s, Baird, op. cit. 517. Type, Arcicola aitsleriit heC. ' ' 



> Ckilolui, Baird, op. cit. 510. Typo, Arvioola oregoni Bach. 



The foregoing synonymical list of itself indicates the limits we wish to set 

 to Aroicola. All the earlier names, Mus, Lemmus, Myodes, Arcicola Lacdp., 

 and Hypudeeus III, marked <, were of wider applicability than Arvicola, as 

 wc define it, is-, for they all (unless Aroicola Lacdp. be an exception) 

 included the Lemmings, and made no distinction of the rooted-molar species 

 of what Keyserling and Blasius afterward called Hypudeeus, and what we 

 now call Evotomys. The many later names, marked >, are of less enlarged 

 application than our Arvicola, being simply based upon particular species of 

 the genus; most of them will stand as convenient subgeneric terras for the 



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