MURID.E— ARVICOLINJE— ARCTIC ARVICOL2E. 



195 



indeed, of this series touch the average (0.79) of United States riparius, the 

 rest being between 0.65 and 0.75; whereas the United States riparius^ feet 

 apparently never fall below 0.70, and may range from 0.80 to 0.90. 



The following is an enumeration (we did not think it necessary to tabu- 

 late) of the specimens in the present series that depart more or less noticeably 

 in some respects from ordinary riparius, yet do not show the peculiarities of 

 either borealis or xanthognathus strongly enough to enable us to label them 

 as belonging to either of those forms. We shall simply label them "riparius 

 var. — ?". In general, their absolute size is neither above nor below that of 

 riparius ; few being so small as those we tabulate beyond under head of 

 borealis, and none being as large as the doubtful xanthognathus beyond given. 

 They differ from ordinary riparius principally, as would be expected in these 

 boreal cases, in their smaller members and heavier pelage. 



Nos. 6847, 6849, 6850, 6851, 6855, 6857, 6858, 6859, 6861, 6864, 6866, 

 6867, 6870, 6872, 6873, all collected by Mr. Kennicott on the Yukon, at the 

 mouth of Porcupine River. They run directly into the specimens from the 

 same locality, tabulated beyond as borealis. 



Nos. 6832, 6881, 6882, 6876, 6889, 6887, 6884, 6885, 6886, 6883, 6888, 

 6880, taken by the same explorer in spring, two hundred miles southwest of 

 the last-named locality. Owing to the season, they average remarkably 

 dark-colored. 



Nos. 9157, 9156, 9151, 9152, 9158, 9160, 9164, 9174, 9167, 9159, 9149, 

 9144, 9142, 9161, 9148, 9165, 9150, 9166, 8022, 8025, 8026, 8163, 8755. 

 Fort Anderson, north of Great Bear Lake; R. McFarlane. 



Nos. 6836, 6937, 6841, 5749, 9194, 6842, 6834, 6839, 9193, 9114, from 

 Anderson River; R. McFarlane. Some of these, as 6841, run very close to 

 certain styles of xanthognathus. 



Nos. 9109, 9122, 8820, 9213, 9205, 9126, 9101, 9187, 9127, 9123, 9206, 

 9130, 9217. This lot was received by Mr. McFarlane from the Esquimaux 

 of McKenzie's River, and is less homogeneous than either of the preceding. 



Nos. 8037, 8027, 8041, 8031, 8045, 8032, 8040, 8050, 8029, 8052, 

 8038, 8049, 8043, 8054, 8042, 8045, 8044, 8030, 8046, 8039, 8034, 8036, 

 8035, 8028, 8053. From the Arctic coast, brought by Esquimaux to Mr. 

 McFarlane. 



