MURIDA—ARVICOLINA—ARCTIC ARVICOLA. 1a 
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 zanthognathus 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, 915%, 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. 
