27 



characters need not be here recapitulated. The several ascribed 

 species of North American Mijodes proper are reducible to the 

 following, which is not specificall}^ separable from that of Asia. 



1. Myodes obensis, Brantz. 



Syn. Ml/odea obcnsifi, Brantz, Muisen, 1827, 55. — Keys, and Bias., Werb. 



Eur. vi. 1840, pp. vii. and 32. Midd., Sib. Reise, ii. 1853, 91), pi. ii. 



figs. 7, 8, 9, pi. viii. pi. ix. and pi. x. f. 2.— Baird, M. N. A., 1857, 



559. 

 Arvicoln {Georychus) Jtelvolus, Rich., F. B. A., 1829, 128. 

 Oeorychus Jieholu.% Aud. & Bacb., Q. N. A. iii. 1853, 84, pi. cxx. f. 1. 

 Myodes helvolun, Dall, Alaska and its Res. 1870, 577. 

 Aivicola (^GeorychuK) tnnmcronatus, Rich., App. Parry's 2d Voyage, 



1825, 309 ; F. B. A. i. 1829, 130. 

 Oeorychus tritaucroiuitus, Aud. and Bach., Q. N. A. iii. 1833, 8G, pi. 



cxx. f. 2, 3. 

 Myodes trimucronntu.fi, Dall, Alaska, 1870, 577. 

 Myodes albogvlaris, Wagner, Suppl. Schreber, iii. 1843, 602. 



Hob. More western portions of Arctic America. 



Obf;. Of this species I liave handled about forty specimens, the 

 first examined by an American naturalist for many years. They 

 differ somewiiat from the only two Siberian skins before me, pos- 

 sibly representing a variet}^ (to be called 31yodes helvolus) ; but I 

 am far from disputing Von Middendorff's decision as to their 

 specific identity with the Asiatic animal. 



Genus IX. CUNICULUS, Wngler. 



Syn. 3/«s, Arvtcola^ Myodes et Lemmui^, Anctt. — Oeorychus, partim, Rich., 

 Aud. and Bach., vec lll.—Cuniculus, Wagler ("1830"), Isis, 1832, 

 1220; type C. grGinlandkus= G. torquatics ov hudsonius. — Lilljeborg, 

 Syst. Otvers. Gnag. Glires, 1866 (same type). 

 Obs. Without going into the characters of a perfect)}' well- 

 known form, I wish to particidarly signalize the fact tliat this 

 genus, though based upon a " lemming," is very different from 

 llyodei^, and, indeed, from any other arvicoline type. Tlie molar 

 pattern is strongly of an ordinary arvicoline general character — 

 not at all as in Myoden or Synaptomys — while details of the molar 

 dentition (as, for instance, six prisms on back upper molar and 

 nine on front lower molar) are unique. The obsolete ear and 

 pollex, tlie singular hypertrophy of tlie two middle fore claws, and 

 the notable seasonal changes of pelage, are all peculiar. I find 

 but one American species, identical with that of Asia. A second 

 supposed species, C. lagiirus, I have not seen. 



