528 GRISON, 
Fia. LXXIV. GRISON (GALICTIS) CANASTER. NELSON'S GRISON. 
No, 6420 Mus. Comp, Zodl, Coll. 
outer side, 9; length of mandible, 47; height at condyle, 10; at coro- 
noid process, 23; length of lower tooth row, 23. (Specimen from 
Orizaba, Mexico, Coll. Mus. Comp. Zoél. Cambridge, Mass.) 
The genus Purorius is a large one, and contains the true Weasels, 
Ferrets, and Mink, and is divided into several sections having sub- 
generic values. The largest number of species are included in the 
true Weasels here placed under the subgeneric term, Arctogale, the 
members of which living in boreal regions turn white in winter. 
Great difference is observable in size between males and females, the 
latter being very much smaller. The Arctic weasel is valued for its 
fur, which is the well-known ermine of commerce. The weasel is 
remarkable for its long, sinuous body and neck, flat serpentlike head, 
short legs, and a moderately long tail. It is wonderfully quick in 
its movements, and in the pursuit of its quarry is able to enter any 
hole or penetrate any underground gallery in which its prey may 
have sought refuge, the lithe, flexible body accommodating itself to 
all the twists and turns met with. Possessed of good sight, it follows 
a fleeing animal at full speed, but when its prey is lost to view it then 
tracks it by its keen scent, exhibiting all the tactics of the well- 
trained hound, doubling on its course and following every movement 
of the creature hunted, and when the track is momentarily lost, 
making wide circles in order to strike it again. In the chase of any 
animal the weasel is indefatigable, and few escape its relentless pur- 
