M U Rl D^— Alt VICOLIN^— PEDOM Y8. 



209 



NoTR.— Noa. 8370-71, apparcDtly nf this apecicH, oro too youog fur positive IdeDtiflcation. The teeth are scarcely cut ; 

 but, so far as wo cmi Jutlge, the back upper molar tvlll have but one external closed triaogle, and a posterior Y-sbaped treflSe. 

 The meataa SMms to bo anrroandetl by a faint rim, bnt the tipper margin of the ear is not inflectetl, the concha being per- 

 fcctly flat. 



Subgenus PEDOMYS, Baird. 



Anleola sp., Adctorum. 



= PnIoiiiyi, Baird, M. N. A. 1857, 517 (type, ArvieoXa auttervf LeC.)-— Codes, Proc. Acad. Nat. Sci. 

 Phila. 1874, 190. 



Chars. — Postero-superior molur with an anterior transverse loop, two 

 interior triangles, one exterior triangle, and a posterior U-, V-, or Y-shaped 

 loop (as in Pitymys and Chilotui). Medio-snperior molar with an anterior, 

 two exterior, and only one interior triangle (lacking tlie supplementary postero- 

 interior spur or triangle of Myoitomes). Antero-inferior molar with a posterior 

 transverse loop, two interior closed triangles, one exterior closed triangle, 

 another exterior and another interior open triangle, and an anterior irregular 

 trefoil. Other molars as in Arvicola at large. Ears concealed, without 

 inflected margin of conch or rim in front of meatus ; antitragus highly val- 

 vular, as usual. Tail in the type of the subgenus about equal to the head 

 (about one-third the head and body), in other species not more than one- 

 fourth tlie trunk, and thus as sliort as in Pitymys. Perfect plantar tubercles 

 only five. No special cranial characters, and external form as in Myonomes 

 (except shorv«^r tail), or much as in Arvicola at large. Pelage grizzly and 

 rather "austere"; the under parts usually with a i)eculiar muddy tinge. 



Under head o^ Arvicola we have already diagnosticated this section, and 

 after the further remarks just made there is little to say. There are no tan- 

 gible cranial characters ; and, as lO the external characters, they are with diffi- 

 culty describable as any different from those of Myonomes ; but the tail is 

 shorter, and the animals appear to be even more squat and bunchy than M. 

 riparius. There are only five perfect plantar tubercles, though the rudiment 

 U M 



