152 MAMMALIA. 
The islands in the straits of Sunda produce a rat-mole as large as 
a rabbit, of a deep grey colour, with a white longitudinal stripe on 
the head, the Spalax javanus. 
From the rat-moles themselves should have been separated the 
Batuyeraus, Iilig.—Orycrerss, Fr. Cuv. 
The Orycteres, which, with the general form, feet, and truncated inci- 
sors of that genus, have four grinders throughout. Their eye, though 
small, is visible, and they have a short tail. 
B. maritimus; Mus maritimus, Gm.; Taupe des dames, Buff. 
Supp. VI. xxxviii. (The Maritime Rat-Mole). Nearly the size of 
a rabbit; the superior incisors furrowed with a groove, and the hair 
of a whitish grey. 
B. capensis; M. capensis, Gm.; Taupe du Cap., Buff. Supp. VI. 
xxxvi. (The Rat-Mole of the Cape). Hardly as large as the 
guinea-pig; brown, witha spot round the ear, another round the eye, 
and a third on the vertex; the end of the muzzle white. The inci- 
sors are smooth. 
B. hottentottus, Less. and Garn., Voy. de la Coquille, pl. ii. (The 
Hottentot Rat-Mole). Smaller; grey; incisors smooth; hardly as 
large as arat. We must approximate to the Rat-Moles (Spalax 
and Bathiergus). 
Geromys, Rafin.—Psrupostoma, Say.—Ascomys, Lichten. 
The Geomys, which have four molars in compressed prisms throughout ; 
the first double, the remaining three simple ; the upper incisors furrowed with 
a double groove in front; five toes to each foot; the three middle anterior 
nails, that of the medius particularly, very long, crooked, and trenchant. 
They are low animals, and have very deep cheek-pouches, which open ex- 
ternally, enlarging the sides of the head and neck in a singular manner. 
One species only is known. 
G. bursarius; Mus bursarius, Shaw.* (The Canada Hamster). 
Size of a rat; fur of a reddish-grey; tail naked, and but half the 
length of the body. Inhabits deep burrows in the interior of North 
America. 
Dirtostoma, Rafin. 
The Diplostome are in every respect similar to the Geomys, except 
that they have no tail.+ 
These animals are also from North America. The species before 
us is reddish, and ten inches in length. 
We now pass to larger Rodentie than those of which we have hitherto 
* The figures of this animal, first published Trans. Lin. Soc. Vol. V. pl. viii, and 
Shaw, Vol. II. part 1, pl. 138, represent it with the internal skin of the cheek-pouches 
turned inside out, as though it had two sacs to the sides of the head. There is no- 
thing like it in nature. - It is well represented, Acad. Berlin, 1822 and 1823, pl. ii. 
+ M. Rafinesque describes them as having only four toes to each foot, The-Eu- _ 
yopean species has five, like the Geomys. 
