from each other by a naked farrowed septum, and surrounded by a small naked space ; their
inner margins are a little arched or ventricose.
The mouth is small, being contracted by an union of the lips behind the upper incisors.
The cheek-pouches are large and. pendulous,, thinly- clothed with short hairs, or sometimes
almost naked, opening into the mouth by the side of the molar teeth.
The eyes are small and far apart. There is no other external ear than a slightly raised
margin to the auditory openings, which are large.
Body cylindrical. Tail of moderate length, round and' tapering, more or less hairy.
Extremities short, with five short foes to each foot. The palms are naked, and have a
remarkable callous protuberance,, projecting like a heel at their posterior part. The second
and fourth toes are united nearly the whole length of their first phalanges to the middle one
by skin. The fifth toe is considerably smaller and’ much further back than these, and the
thumb is the smallest of all, and is situated a little further back than the fifth toe. The foreclaws
are. long, compressed towards their roots, slender and awl-shaped near their points,
acute and considerably curved ; the middle one is the longest, the thumb one is small and
more blunt, and the others are of intermediate sizes, proportionable to the length of their
respective toes. The hind-feet are more slender than the fore-ones, and their soles, which
are entirely naked, are narrower than the palms. The outermost and' innermost hind-toes
are situated further back than the other three, of which the middle one is the longest. The
hind-claws are much shorter and more obtuse than the fore-ones, are excavated underneath,
and are but slightly compressed..
The fu r resembles in quality that with which the meadow-mice are clothed-. The tail and
feet are covered' with shorter and coarser hair;
Habit.—The sand-rats burrow in sandy soils and feed’ on acorns, nuts, roots,
and grass, which they convey to their burrows in their cheek-pouches. They
throw up little mounds of earth like mole-hills, in the summer, but are not seen
abroad in the winter, nor do they throw up earth during that season. Their
pouches when full have an oblong form, and nearly touch the ground, but when
.empty they are retracted for three-fourths of their length. Their interior is very
glandular, particularly round the orifice that opens into the mouth.
Remarks jg-M. Rafinesque-Smaltz, in 1817, founded his genus geomys-on the
hamster of Georgia (geomys pinetis), described by Mitehill, Anderson, Meares,
and others, and referred to it, as a- seeond species, the Canada pouehedi-rat
(mus bursarius of Shaw) . He at the same time ranged under another genus,
pamed by him diplostoma, some Louisiana or Missouri animals, known to the
'Canadian voyagers by the appellation of gauffres, and remarkable for their large
cheek-pouches, which open forwards exterior to the mouth and incisors, to which
they form a kind of, hood. These two genera have been adopted by few
naturalists; and the American systematic writers have either overlooked M.
Rafinesque’s species entirely, or referred them all to the mus bursarius. In the
latter case, they are undoubtedly wrong, for there are at least six or seven distinct
species belonging to one or other of these genera, which inhabit America ; and I
think that both geomys and diplostoma will eventually prove to be good genera: —
the Sand-rats belonging to the former having cheek-pouches, which are filled from
within the mouth, and the gauffres or camas-rats of the latter genus having their
cheek-pouches exterior to the mouth, and entirely unconnected with its cavity.
I have had no opportunity of examining the geomys pinetis, which is the type of
the genus; but Mr. Leadbetter, with his wonted liberality, has permitted me to
inspect an individual of a hitherto undescribed species from Cadadaguios ; and
Mr. David Douglas very kindly sent me a specimen of another species, which he
captured on the banks of the Columbia, and which forms the subject of the
following article. From these two the characters of the genus, given in the preceding
pages, were drawn up, the description of the teeth, and the views of the scull,
being made from the latter. With regard to the-Canada pouched-rat, great doubt
still exists as to whether it belongs properly to geomys or to diplostoma. It was
first described by Dr. Shaw, and an engraving published in the Linnean Transactions,
from a drawing by Major Davies, of a specimen sent to,Governor Prescot,
from the interior of Canada. Judging merely from that figure and description, I
should have little doubt of the cheek.pouches qpening into the mouth, and of their
being precisely similar in form-and functions to the cheek-pouches ofithe sand-rats;
but I have been told, on good authority, that the identical specimen described by
Shaw (and which, on the dispersion of Mr. Bullock’s collection, passed into the
hands of M. Temminck) is, in fact,-similar to the ganf&es, in having cheek-pouches
that open exteriorly, and that consequently Major Davies’s drawing represented
them in an unnatural, inverted .position. Mr. Say, under the generic name of
pseudostotna, gives the characters of a Missouri gauffre, with cheek-pouches
opening exteriorly, and he identifies his specimen with the mus bursarius. He
alludes to the Georgia hamster, as belonging to the same genus, without giving
any further account of its characters than merely quoting Dr. Barton’s remark, of
its being only half the size Of the Missouri one. His account of the dentition of the
Missouri gauffre corresponds, as far as it goes, pretty closely with that of the
Columbia geomys. Dr. Harlan and Dr. Godman refer the Georgia, Canada, and
Missouri animals, to one species.