MAMMALIA, 201 
DIMENSIONS. 
Inches. Lines. Inches. Lines, 
Length of head and body . . 6 G | Length of the middle fore-toe, excluding the 
45 head « . . 1 10 claw . 5 5 a 0 4 
os tail (vertebre) . 6 i? 10 > from the heel to end of middle claw, 
WSS cheek-pouches . 3 I 3 measured along the sole . A ay eds 2 
Diameter of cheek-pouches, about . 0 6 Dimensions of the scull. 
Distance from the end of the nose to the eye 0 11 | Length from the extremity of the upper jaw 
5 x of the nose to the to the occipital crest (by calipers) ao wl 6 
auditory opening : a wl 8 Breadth, including the zygomatic arches 1 0) 
5» between the eyes . ; 0 ai ) of frontal bone between the orbits . 0 3 
Length from wrist-joint to end of the middle- Length of the lower jaw from the condyles to 
claw . e ° c « | 0 its anterior extremity 2 ‘ Row 0 
Prater xvitt C. 
Fig. 1, 2, and 3. Views of the scull (nat. size.) Fig. 5. View of the palate and upper teeth (magnified. 
' -— 4. View of the lower jaw (nat. size.) — 6. View of the first upper grinders (maguified.) 
The specimen here described is a female, which was taken in her nest, with 
three young ones, by Mr. Douglas, near the mouth of the Columbia. When put 
into my hands, the fur had mostly fallen off, but the specimen was in other respects 
perfect, and what was wanting has been supplied in the description from Mr. 
Douglas’s notes. ‘The state of ossification of the scull shewed the animal to be 
an old one. Mr. Douglas acquaints me, that the outside of the pouches was 
cold to the touch, even when the animal was alive, and that on the inside they 
were lined with small, orbicular, indurated glands, more numerous near the 
opening into the mouth. When full, the pouches had an oblong form, and, when 
empty, they were corrugated or retracted to one-third of their length ; but 
they are never inverted so as to produce the hood-like form of the pouch of 
-a diplostoma. When in the act of emptying its pouches, the animal sits on its 
hams like a marmot or squirrel, and squeezes his sacks against the breast with his 
chin and fore-paws. 
These little sand-rats ‘are numerous in the neighbourhood of Fort Vancouver, 
where they inhabit the declivities of low hills, and burrow in the sandy soil. 
They feed on acorns, nuts (corylus rostrata), and grass, and commit great havoc in 
the potatoe-fields adjoining to the Fort, not only by eating the potatoes on the 
spot, but by carrying off large quantities of them in their pouches. The specific 
name is a small tribute of respect for the zeal and intelligence of its active and 
diligent discoverer. | 
2D 
