MUUID^E— AEVICOLESLE— ARVICOLA. 1 53 



B. — Cuilotus. Back upper molar with 1 external triangle and a posterior 

 trefoil. Middle upper molar with 1 internal triangle. Front lower 

 molar with 3 internal and 2 or 3 external triangles. Ear with a rim in 

 front of the meatus, owing to meeting there of the anterior and poste- 

 rior roots of the auricle. Sole 5-tuberculate (?). Fore claws not larger 

 than hinder ones. Tail about J the head and body. Pelage ordinary. 

 Of minimum size. 



C. — Pedomys. Back upper molar with 1 external triangle and a posterior 

 trefoil. Middle upper molar with 1 internal triangle. Front lower 

 molar with 2 internal and 1 external triangle. Ear un rimmed. Sole 

 5-tuberculate. Fore claws not larger than hinder ones. Tail about J 

 the head and body, or a little less. Pelage ordinary. Of medium size. 



D. — Pitymys. Back upper molar with 1 external triangle and a posterior 

 trefoil. Middle upper molar with 1 internal triangle. Front lower 

 molar with 2 internal and 1 external triangle. Ear unrimmed. Sole 

 5-tuberculate. Fore claws larger than hind ones. Tail about | the 

 head and body, or less. Pelage dense, mole-like. Of small size. 



Subgenus MYOTOMES, Rafmesque. 



< Arvicola of American writers. 



=Armeola A, Hemiotomys, Baird, M. N. A. 1857, 515 (type, Arvicola riparius Oiu>). Not of Selys-Long- 



ciiamps, whose type is the European Arvicola amphibius. 

 = Mynomcs* Rafinesque, Am. Monthly Mag. ii, 1817, 45 (type, Mj/iiomes pratensis Rafinesque, which 



is hased on Wilson's Meadow-Mouse, Am. Orn. vi, pi. 50, f. 3, and is therefore = Arvicola 



2)ennsylvanica Orel aud auct.). 

 = Myonomcs, Coues, Proc. Acad. Nat. Sci. Phila. 1874, 189. 



Chars. — Posterior superior molar with an anterior loop, an internal 

 closed triangle, two external closed triangles, and a posterior crescent. Ante- 

 rior inferior molar with a posterior loop, an anterior trefoil, three lateral inter- 

 nal closed triangles, and two "(or threef) lateral external closed triangles. 

 Middle superior molar with a supplementary postero-internal triangle. (Other 

 dental and cranial characters as in Arvicola at large.) Ears about equaling 

 the fur, rounded, hirsute, with well-developed valvular antitragus; no pecul- 

 iar construction of the concha. Tail exceeding the head in length (about 

 one-third as long as head and body), fairly hirsute and with terminal pencil, 



* The original orthography is Mynomes. I do not know what, if any, meaning attaches to this 

 word, hut suppose it to he compounded with /ivc, so that it should he spelled Myonomcs, if not further 

 altered into Hyonomus. 



t When there are three, the third results from change of the outer leaflet of tho anterior trefoil 

 into a triangle. 



