81 
GENUS GEOEYCHUS.- Illiger. 
DENTAL FORMULA. 
Incisive \ ; Canine ~ ; Molar =16. 
This sub^ -anus in its dental formula is similar to Jlrvicola j eyes, very 
small ; ears rising slightly above the auditory opening ; thumb, conspicu- 
ous ; nails on the fore feet fitted for digging ; tail, very short. 
Natives of cold climates, burrow in the earth, feed on seeds, roots, and 
grasses. 
Ten species are admitted by naturalists, two of which are in Europe, four 
in Asia, and four in America. 
The generic name Georychus was given by Illiger, from 
digging the earth. 
GEORYCHUS HUDSONIUS . — F orstee 
Hudson’s Bat Lemming. 
PLATE CXIX. — Winter and Summer Pelage. 
G. Auriculis nullis, maniculorum unguibus duobus intermediis, maximis, 
compressis, quasi duplicatis, per sulcum horizontalem divisis j colore in 
asstate rufo-fusco, in hyeme albo. 
CHARACTERS. 
Earless . the two middle claws of the fore feet unusually large , compressed , 
their blunt extremity being rendered double by a deep transverse notch. Colour 
reddish-brown in summer, white in winter. 
SYNONYMES. 
Mus Hudssnius. Forster, Phil. Trans., vol. lxii. p. 879. 
“ “ Pallas, Glires, p. 208. 
“ “ Linn. Gmel. 137. 
Hudson’s Eat. Pennant, Quadrupeds, vol. ii. p. 201. 
“ Arctic Zoology, vol, i. p. 132. 
Hare-tailed Mouse. Hearoe’s Journey, p, 387. 
VOL. Ill, — 11 
