[62.] i t Geomys Docglash. (Rich.) Columbia Sand-Rat.
G. (Douglasii), super fuligneus suiter pedibusque pallidior, cauda dimidi-um corporis superanti.
Columbia Sand-rat, of a dusky-brown colour above, paler beneath, and on the feet, with a tail exceeding half the body
in length.
Plate xyiii C. Fig. 1 to 6.
D E S C R I P T IO N .
The head is large and depressed ; the nose obtuse, particularly when viewed sideways. The
nostrils are small and round, situated at the extremity of the nose, and separated by a
furrowed septum about a line wide; they have a small naked margin, and the narrow upper
lip betwixt them and the roots of the upper incisors is covered with short hair. Mouth
moderately large ; lips hairy. Incisors, strong, exserted, orange-coloured; upper ones with a
fine but distinct furrow on their anterior surface, close to their inner edges ; lower ones with
a similar furrow on their sides, close to their outer edges. Cheek-pouches large; much
resembling the thumb of a lady’s glove, in form and size, and hanging down by the sides of
the. head ; they have a pale buff-colour, and are of a soft membranous texture, nearly bare
outside, having merely some very short, soft, scarcely visible, white hairs, scattered over them,
with a reticulation of darker nerves: within they.appear glandular, and their openings into
the mouth are sufficiently wide to admit the point of the little finger, being nearly equal-to
the diameter of the pouch itself. The fore-side of the pouch is posterior to the eye, and the
hind-side is opposite to the e a r; its tip, which must touch the ground when the animal walks,
is very obtuse. The whiskers are short and. soft, jg
Body, shaped like that of a mole, and covered with short, soft, dense, velvety fur, of an
uniform dusky-brown colour. The fur on the belly and feet has a lighter hue. Tail, more
than half the length of the body, round, tapering, and obtuse ; covered with hair, particularly
near its root.
■ Legs, short and thick. Fore-toes short, but very flexible; the three middle ones united at
their bases by skin ; the outer one is smaller and further back, and the thumb is very small,
but is armed with a claw similar in form to the others, though it is much smaller. The claws
are very sharp-pointed, compressed, curved, and about as long again as their respective toes.
The palm is naked, and its posterior part is filled by a large, rounded, callous eminence.
The hind-feet are a little more slender than the fore-ones, and they are armed with smaller
claws, shaped like those on the hind-feet of the spermophiles. The hind-soles are entirely
naked, without any conspicuous tubercles ; the heel is naked and narrow.
D im e n s io n s .
i aches. Lines.
Length of head and body . 6 6
„ ., head . • • 1 10
, ,, tail (vertebrae) . . 2 10
. „ cheek-pouches 1 3
Diameter of cheek-pouches, about • 0 6
Distance from the end of the nose to the eye 0 11
,, of the nose to the
auditory; opening. •-
, „ between the eyes
Length from wrist-joint to end of the middle-
claw . • ' » ■ *
I
0
1
8
7 ’
p
Length of the middle fore-toe, excluding the
claw . . . . 0
„ from the heel to end of middle claw,
measured along the sole . . . 1
Dimensions of the scull.
Length from the extremity of the upper jaw
to the occipital crest (by calipers) . I
Breadth, including the zygomatic arches 1
„ of frontal bone between the orbits . 0
Length of the lower jaw from the condyles to
-jts anterior extremity . . . 1
4
2
603
0
P l a t e x v i i i C.
Fig. 1, 2, and 3. Views of the scull (nat. size.) : I 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 (magnified.)
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