Rodentia. MAMMALIA. Rodentia. xcix 
Cricetodipus. — Baird. 
This genus embraces qiiitediiniiiutive animals, with 
liairy soles. 'I’lie antitragus of tlie ear has no lobe. 
YELLOW POCKET MOUSE [C.fiavxis, Baird).—' \!\\\B 
is mucli smaller than Mus musculus. The head and 
body measure two inches in length; tail the same. 
'I’lie ear is small, nearly concealed. The color above 
is a jiale bulf, blended intimately with blackish ; 
below, including- the whole of the fore-leg, pure white. 
The sides have a clear bulf stripe. The tail is ob- 
scurely bicolor. About the ears are seen a few 
white spots. Habitat, the Rocky Mountain region, 
and south to Mexico. The pelage is very fine and 
glos.sy. 
LEAST POCKET MOUSE {G. parms, Baird) {and 
Beale?) — 'J’his is like the jireceding, but has longer 
feet and tail. The habitat is the same. 
Sub-Family— DIPODOMYINiE. 
In this sub-family the molars are rootless; the 
anterior molar a simple prism. “The mastoids are 
e.xtraordinarily developed, even for this family.” 
The tympanic is completely bullous ; soles of the feet 
densely hairy, like those of the Rabbit. The hind 
limbs are elongated, like those of the Jerboa, and 
formed for jumping. The pelage is comparatively 
soft for the family. 
Dipodom Ys. — Gray. 
The skull in this genus is light, p-apery, thin, de- 
[iressed and tapering in front. The snout is pointed, 
[irojecting beyond the incisors. The lachrymals are 
greatly excavated ; the mastoids extremely enlarged. 
The superior incisors are sulcate, and point strongly 
backwards ; they are deeper than wide. Molars are 
simple and rootless. The general form is Jerboa- 
like, the hind-legs being very long. The tail is 
rather longer than the head and body. The eyes are 
large and full ; the ears large and round. The whis- 
kers are half as long as the whole body ; the upper 
lij) not cleft ; ample cheek pouches ; the pelage long 
and very soft. 'I'he size is that of a half-grown Rat. 
The dentition is simple. The incisors are small and 
delicate in both jaws, the upper being compressed ; 
a deep groove runs down the centre of each., 
KANGAROO RAT [Dipodomys phillipsi. Gray).— 
'J'his delicate and graceful creature is found in the 
region of the Pacific slope. It is small, rather under 
four inches in length, slender, with large ears, long- 
limbs, and especially long tail. 
ORB’S POCKET RAT {D. phillipsi ordi, Woodh.)— 
This was described by Prof. Baird as D. montanus, 
and also as 1). ordi. It is found in the Rocky Moun- 
tain region, and eastward, reaching- into Mexico. It 
is larger than the preceding. 
Family— G EOMYID^. 
Animals embraced in this family are found in the 
cold-temperate and warmer regions of continental 
America. 
Guomys. 
This genus includes the forms having the superior 
incisors deeply channeled along the middle. The 
external ears are usually a mere vein of integument 
around the orifice. The fore-claws are enormously 
developed. The ])Ouches are not pendulous, as was 
first supposed ; they are wholly external, and lined 
with the fur of the integument. 
COMMON POCKET GOPHER [Geomys hursarius, 
(Shaw) Rich.) — This novel creature abounds in the 
region about the Mississippi River, from Texas 
northward to Ganada. Its length is seven to eight 
inches ; the tail about two or three. The pelage is 
soft and Mole-like. Its specific name refers to the 
curious pocket or sack which is present in this group 
of animals on each side of the neck. 
THE FLORIDA POCKET GOPHER (Geomys tuza. 
(Ord) Goues). — 'I'liis was described by Bartram as 
the Ground-rat. It is known more generally as the 
Salamander — an absurd name, as the latter is more 
properly a reptilian term. Mitchell called it Ham- 
ster, and Aud. and Bach, the Southern Pouched Rat. 
It is about the size and shape of the preceding, and 
is regarded as a “ localized race ” of the same. 
THE PECOS, OR CHESTNUT POCKET GOPHER 
(Geomys castanops, (Baird) LeGonte). — 'J'his is a rare 
form, found in 'i'exas and New Mexico. Its color is 
a pale yellowish-brown above, inclining more or less 
to dull chestnut about the head ; below, it is whitish. 
It is rather less in size than the preceding. 'The 
fore feet are shorter than the hind ; the feet and tail 
nearly naked. “The superior incisors with a single 
median groove bisecting the face exactly.” 'I'liis 
feature of the front teeth gives an appearance of 
four incisors instead of two ; the latter are orange 
colored. 
THE TUCAN, OR MEXICAN GOPHER (G.mexicamis, 
(Licht) Rich.) is a Mexican species, with the color- 
ation much like the bursarius, but is much larger 
than any of the United States species. Its pouches 
and hands are proportionally smaller. Its length is 
from ten to eleven inches ; tail about three. 
THE QUACHIL (Geomys hispidus, LeGonte) is 
found in Mexico and Central America, whore it is 
called Central American Pocket Gopher. Its most 
noticeable feature is seen in the nakedness of the tail 
and feet; the former being, in some cases, entirely 
bare. 'I'he hispid nature of the pelage is another 
prominent feature, being coarse, harsh and lustreless; 
it is long, and interspersed with stiff hairs The 
pouches are moderate in size. “'I'he superior incisors 
with a single strong, deep furrow, lying wholly in the 
inner half of the tooth.” 
'I'ho.momys. — Max. 
This genus presents the following characters: 
“ I'he superior incisors are without a median sulcus, 
but have a fine marginal groove (sometimes obsolete); 
the crowns ot the intermediate molars acutely edged 
exteriorly. The roots ol the inferior incisors cause a 
protuberance on the outside of. the base of the con- 
dylar ramus, nearly as high as the condyle itself ; 
