LEMMUS 209 



Type locality. — Shores of Point Lake, Mackenzie, Canada. 



Range. — Eastern Boreal North America, ranging northwards 

 to Fort Anderson and the Arctic Coast, eastwards to the southern 

 and western shores of Hudson's Bay ; and north-east to the 

 neighbourhood of Repulse Bay and in Baffin Land to the 

 Cumberland Peninsula. 



Characters. — Essential cranial, dental, and external characters 

 as in L. obensis. Fur soft and line, from 13 to 19 mm. long on 

 back. Colour of head and anterior portion of back mixed reddish- 

 grey, produced by the mingling of clove-brown, yellowish-brown, 

 and black hair-tips in nearly equal proportions; posterior part 

 of back chestnut brown, many of the longer hairs being tipped 

 with black ; sides reddish orange ; under parts grey, intermixed 

 with many yellowish orange hairs. Nose deep black. Ears 

 somewhat shorter than fur, thinly clothed. Tail clothed with 

 stiff hairs, bicoloured, dark brown above, greyish-white or 

 yellowish below, its terminal pencil about 9 mm. long. Feet 

 dusky brown above, lighter below. 



Preble notes, from specimens collected near the mouth of the 

 Thiewiaza River, Hudson's Bay, that the " rusty ochraceous " 

 of the lower parts and sides extends forwards on the '' cheeks 

 and lips, sometimes tinging slightly the head and shoulders " 

 and he adds : "In some of the half-grown specimens in fresh 

 pelage the head and shoulders are considerably flecked with the 

 colour of the sides and there is an indistinct dusky stripe extending 

 from between the ears to the middle of the back. Younger 

 specimens are nearly unicolor throughout, the plumbeous fur 

 tipped with yellowish-brown." 



For external and cranial measurements, see tables at end of 

 volume. 



Remarks. — Richardson states that the type collected June 26, 

 1821, was a female containing six fully formed but hairless 

 embryos. Preble found that a few females, taken August 4-8 

 (the breeding season being then nearly over) at Thiewiaza River, 

 contained from four to six embryos; and that the mammary 

 formula is 2 — 2 = 8 as in other members of the genus. 



10. Lemmus helvolus Richardson. 



1828. Arvicola (Lemmus) helvolus Richardson, Zool. Journ., 3, p. 517. 



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

 Amer., p. 128. 



1848. Myodes helvolus Gray, P.Z.S., 1848, p. 43. 



1853. Myiuk.'^ vhensis Midilcndorlf, .Sibirische Reise, 2, Th. 2, p. 107; 



Baird, Mammals N. Amor., p. 559, 1857; Coues, Men. N. Amer. 



Rodentia, ]Murid£e, p. 241, 1879 (in part). 

 1908. Lemmus helvolus Preble, N. Amer. Fauna, No. 27, p. 182; 



Miller, •■ List," 1912, p. 200, and " List," 1924, p. 396. 



Type.—V>.U., No. 42.10.7.11 ; subadult, collected by Thomas 

 Drummond 1826, presented by Sir J. Richardson. 



