MURID.E— ARVJCOLUSLE— ARCTIC ARVICOLvE. 191 



("tinged with red" — A. & B.); "a slightly hairy scaly tail more than half the 

 length of the head . . . ItV (according to A. & B. only 1.00); "above dark 

 brown"; "head and body 4tV, &c. Audubon's figure shows a bricky-red 

 animal all over, with an extraordinarily short tail. But the tints of his plates 

 are thoroughly unreliable, and measurements of the type sent us by Dr. 

 Sclater are, — head and body 5.50, tail 1.50; while the same gentleman speaks 

 of the color as "above, rather dark mouse-brown; beneath, much paler, 

 grayish' 1 . Some of Richardson's expressions point to Evotomys rutilus, and, 

 indeed, it seems almost impossible that he should not have included this 

 abundant animal in checking off" his five common species; but other charac- 

 ters assigned are totally incompatible. We should further remark that the 

 ascribed length of the hind foot, 0.55, is less than we ever found for any 

 species excepting the diminutive A. oregonus. We find it impossible to iden- 

 tify Richardson's " noveboracensis? Raf." 



A. " pennsylvanicus Ord" is another of Richardson's species; it has 

 usually been assigned to the ordinary pennsylvanicus of the United States 

 (=. riparius), and in all probability belongs there. He says it is "very 

 abundant from Canada to Great Bear Lake", in which region we are pre- 

 pared to show that the true riparius occurs ; most of the puzzling specimens we 

 shall presently treat of coming from extreme Arctic and Northwestern areas. 

 It is true that Richardson puts the total length ("3£ inches") under average 

 riparius; but this seems to be an error, for Dr. Sclater' s recent measurement 

 of them shows 4.70, while there is certainly an error (probably typograph- 

 ical) in the ascribed length of head ("2t 3 2 "\ for not even the biggest 

 xanthognathus, 7 inches long, has such a head as this implies. On the whole, 

 there is little risk of error in assigning Richardson's " pennsylvanicus Ord" 

 as a complete synonym of true riparius. We will also bear in mind that 

 Richardson states positively it is what Sabine described in Franklin's Jour- 

 ney under the (erroneous) name, of xanthognathus. 



Of a sixth species, less fully noticed by Richardson, from Bering's 

 Straits, under name of Arvicola rubricatus, we know nothing. But we do 

 not believe that this (or any other Arvicola) ever had the sides (or any other 

 part of the body) "scarlet", as alleged, or even "nearly scarlet", as said by 

 Audubon and Bachman. We believe, however, that this animal will prove 

 to be an Evotomys, very near if not the same as Mus rutilus Pallas, with which 

 Richardson has not shown himself acquainted, though we cannot imagine 

 how he overlooked it, as it appears he did. 



