208 MICROTIN.E 



a narrow median sulcus, but not " pinched in " as in L. alas- 

 censis; rostrum small; zygomata squarely set but not widely 

 spreading, the sides parallel ; interparietal large, usually pen- 

 tagonal ; anterior palatal foramina rather short ; auditory bullae 

 remarkably large and strongly inflated. 



For external and cranial measurements, see tables at end of 

 volume. 



8. Lemmus minusculus Osgood. 

 1904. Lemmus minusculus Osgood, N. Amer. Fauna, No. 24, p. 36; 

 Miller, " List," 1912, p. 206; " List," 1924, p. 396. 



Type.—VK Nat. Mus., No. 119612 (Biol. Surv. Coll.); adult 

 male, collected, September 1, 1902, by W. H. Osgood and 

 A. G. Maddren. 



Type locality. — Kakhtul River, near its junction with the 

 Malchatna River, Alaska. 



Characters. — Size much smaller than in L. alascensis. General 

 colour ochraceous, mixed with black or blackish on upper surface, 

 where the black is usually concentrated to form an indistinct 

 median line from nose to shoulders, nearly clear or tawny on 

 flanks and below. Rump patch hazel or hght chestnut, less exten- 

 sive and less contracted than in L. alascensis or L. trimucronatus. 

 Ears dusky, or occasionally with a few ochraceous hairs. Feet 

 seal brown. Tail variable, sometimes dusky or blackish above 

 and hght buff below, and sometimes nearly uniform pale bufi 

 above and below. 



Skull similar to that of L. alascensis but very much smaller ; 

 zygomata less angular and bowed out; naso-frontal region 

 decidedly elevated and rostrum depressed. Auditory buUse 

 more nearly paraflel, usually more inflated and less incHned to 

 be compressed anteriorly, the basioccipital and basisphenoid 

 correspondingly slender. 



For external and cranial measurements, see tables at end of 

 volume. 



9. Lemmus trimucronatus Richardson. 

 1825. Arvicola trimucronala Richardson, Journ. Parry's Second 



Voyage, App., p. 309. 

 1829. Arvicola {Georychus) trimucronatus Richardson, Fauna Boreali- 



Americana, p. 130. 

 1848. Myodes trimucroJiatus Gray, P.Z.S., 1848, p. 44. 

 1853. Myodes obensis Middendorff, Sibirische Reise, 2, Th. 2, p. 107 



(in part); Baird, Mamm, N. Amer., 1857, p. 559; Coues, Men. 



N. Amer. Rodentia, Murida;, 1879, p. 241. 

 1900. Lemmus trimucronatus Stone, Proc. Acad. Nat. Sci. Philadelphia, 



p. 35; Preble, N. Amer. Fauna, No. 27, 1908, p. 181; Miller, 



" List," 1912, p. 207, and " List," 1924, p. 396. 



Type.—V,.M., No. 42.10.7.13; adidt female, collected by 

 Captain Back, and presented by Sir J. Richardson. 



