MDRID^E— ARVICOLIN^— MYODES OBENSIS. 241 



MYODES OBENSIS, Brants. 



Mi/odes obensis, Brants, Muizen, 1627, 55. — Keyseri.ing and Blasius, Wirb. Europ. vi, 1840, pp. vii and 

 32. — Middendorff, Sibirische Reise, ii, pt. iii, 1853, 99, pi. ii, f. 7, 8, 9, and pis. viii, ix, x, f. 

 2.— Baird, M. N. A. 1857, 559.— Coues, Proc. Acad. Nat. Sci. Phila. 1874, 195. 



Arrieola (Georychus) helvolus, Richardson, F. B.-A. i, 1829, 128. 



Georychus heJeolus, Aud. & Bach. Q. N. A. iii, 1853, 84, pi. cxx, f. 1. 



Myodes helrolus, Dall, Alaska aud its Resources, 1870, 577. 



Avvicola (Georychus) trimucroiiatus, Richardson, App. Parry's 2d Voy. 1825, 309; F. B.-A. i, 1829, 130. 



Georychus trimucroiiatus, Aud. & Bach., Q. N. A. iii, 1853, 86, pi. cxx, f. 2, 3. 



Myodes trimucronatus, Dall, Alaska and its Resources, 1870, 577. 



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



Diagnosis. — M. auriculalus, pollice ungue depresso obtuso ligulato instructor 

 unguibus digitorum mantis 3 tn — 1" elongatis scd simplicis, pedibus modice hir- 

 sutism vertebris caudce pedibus breviuribus; not ceo concolore,Jlavo-ferruginep in 

 capite obscuriore, gastrceo dilutiore, pedibus fuscis. M. lemmo staturd formdque 

 par; long. tot. 4- 6 poll., capitis It— If, mantis cum ungue longissimo f-i, pedis 

 f-i, caudce nudes l-\, caudce comatce f-4. 



Hab. — America Septentrionalis region ibus occidentali-borealibus. Asia. 



Form strictly that of the Norway lemming; ears with a perfectly-devel- 

 oped conch, though small (about \ high on the back, \ from the notch in 

 front) and buried in the fur; fore feet hairy on top, the longest hairs reach- 

 ing the ends of the claws, never much when any longer; palms mostly naked, 

 nearly as in ordinary Arvicola, and tuberculate; pollex obsolete, but in its 

 place a very large appressed strap-shaped claw, with obtuse or truncate end, 

 sometimes showing two or three minute points ("trimucroiiatus"); all the 

 other claws simple (never showing the peculiar quasi-duplication of those of 

 Cuniculus torquatus), arched, acute, longer than in Arvicola, never so decidedly 

 fossorial as in Cuniculus; third finger longest, fourth nearly as long, second 

 reaching to base of third claw, fifth much shorter still; hands, including claws, 

 only about f the feet; feet above, like the hands, hairy to the ends of the 

 claws, or the longest hairs slightly surpassing the claws; soles incompletely 

 furry, the bases of the toes naked; second, third, and fourth toes subequal 

 and longest; fifth about reaching base of fourth; second shorter still. Tail- 

 vertebras shorter than foot, with the hairs equal to or rather longer than foot; 

 copiously comous, the terminal pencil frequently longer than the vertebral 

 portion. Pelage long, fine, soft, and mollipilose, the longer hairs quite lus- 

 trous; whiskers about equaling the head, very delicate, not numerous; muffle 

 completely hairy except the nasal papillae. 



Entire upper parts uniform rich ruddy rust color, sometimes more 



16 M 



