RODENTIA. 
113 
Tlie Black Rat (M. rattus, Lin.), which the ancients have not alluded to, and which appears to have entered 
Europe during the middle ages. It is more than double the size of the Mouse in all its dimensions. The fur is 
blackish [with the ears much larger, and the tail longer, than in the following. There is a brown variety of this 
species, which is common in Paris, and appears to have been figured by M. F. Cuvier as the Surmulot.] 
The Brown Rat, or Surmulot {M. decumanus, Lin.), which did not pass into Europe till the eighteenth century, 
and is now more common in large cities [and elsewhere, except in remote isolated localities,] than the Black Rat 
itself ; it is a fourth larger than that species, and is also distinguished by its brown colour. This animal appears to 
belong to Persia, where it lives in burrows : it was not till 1727, that, after an earthquake, it arrived at Astracan, 
by swimming across the Volga. 
I It would seem that the Black Rat, also, originated in the East ; and these two large species, together with the 
1 Mouse, have been transported in ships to all parts of the globe. 
j [Of the very numerous others, it must suffice to name the huge Bandicoot Rat of India {M. giganteus, 
! Hardw.), which is much larger than the Surmulot. Those indigenous to South America have more complicated 
folds of enamel to their molars.*] Some have spines mingled with their fur, as 
The Cairo Mouse (M. cahirinus, Geoflf.), which has spines on the back in place of hairs, and was noticed by 
! Aristotle. 
I [Only two strictly indigenous British Mice have hitherto been described : the first, extremely diminutive, is the 
Harvest Mouse {M. messorius, Shaw), with short ears, and red fur similar to that of the Common Dormouse : it 
j constructs a beautiful round or pear-shaped nest, attached to corn-stems, or placed in low bushes ; and is remark- 
. able for its tail being slightly prehensile at the extremity. The second is commonly termed the Long-tailed Field 
i Mouse {M. sylvaticus), and might almost form a separate subgeniis ; it rather exceeds the common Mouse 
! in size, with proportionately larger ears, and much larger and very brilliant eyes ; a brown mark in the centre 
! of the chest : it is a pretty and very active species, more generally diffused than the Harvest Mouse, and never 
enters buildings, where the other is often carried with the sheaves.] 
Waxm climates produce Rats, similar in every detail to those of which we have just spoken, except 
I that their tails are more hairy. Such are 
Hypudceus variegatus, Licht., var. flava; Meriones syenensis, Id. To which must be added the Arvicola 
messor, Le Conte ; Arv. hortensis. Hark, or Sygmodon, Say, distinguished however by its hairy ears, like 
I the Otomys. ^ 
I Another group, also with a hairy tail, biit the teeth of which wear away faster, comprises the Hypudceus ohesiis, 
! Licht., the Mm ruficaudiis, Id., and also the Meriones sericeus of the same naturalist, characterized by the 
! projecting ridges of the molars, which alternately catch in each other. 
We have then to group the Neotoma floridanum of Say, or the Arvicola floridana of Harlan, and the Arvicola 
\ gossypina, Le Conte, two species which, size excepted, are very similar even in their colours, and the molars of 
which, provided with roots [after a while], when worn a little, have crowns similar to those of the Arvicolce. [The 
: tail in one of them is covered with hair of tolerable length. Both inhabit North America. 
Reithrodon, Waterh., requires also to be introduced here, distinguished by its grooved upper incisors, its arched 
and Rabbit-like head, great eyes, and large and round ears. Three or four species are known, from South 
I America, where they were discovered by Mr. Darwin. 
j The Pseudomys of Gray is another Rat-like animal, remarkable for inhabiting New Holland : the anterior molar 
of its lower jaw is however more compressed and elongated, and there is a claw on its rudimentary thumb. The 
l| species, Ps. australis, inhabits holes in swampy places, at Liverpool plains. 
It is necessary also to introduce here the Hapalotis albipes, Licht.; Conilurus constrictus, Ogilby; another 
ij rodent from New Holland, the size of a Rat, with delicate ample ears, and a long, hairy, and somewhat tufted tail, 
l! It is remarkable for constructing an above-ground habitation, so firmly interlaced with thorny twigs externally, 
!' as to repel the Dingo or semi-wild Dog of that country.] 
■j 
j The Gerbils {Gerbillus, Desm. ; Meriones, Illig.)— 
I Have molars scarcely differing from those of the Rats, merely becoming sooner worn, so as to form 
I transverse ridges. Their upper incisors are furrowed with a groove ; their hind feet are somewhat 
II longer in proportion than those of Rats in general, with the thumb and little toe but slightly sepa- 
I rated: their tail is [very] long and hairy, [and generally tufted]. 
ij The sandy and warm parts of the eastern continent produce several species, [mostly of a light buff colour, white 
I underneath]. 
j; The Merions {Meriones, F. Cuv.), — ■ 
i Which we separate from the Gerbils, have the hind feet still longer, the tail nearly naked, and a very 
small tooth before the superior molars; characters wdiich approximate them to the Jerboas: their 
superior incisors are grooved, as in the Gerbils, and their toes also are similar, 
j There is a small species in North America, 3Ius canadensis. Pen. ; Dipus canadensis, Shaw ; D. americanus, 
* Certain of these, the upper lip of which is scarcely fissured, com- | South Africa, which constitute the Herarfromys of Smith ; tliey scarcely 
' pose the HofocAt'/us, Brandt. There are also some arboreal Mice in I differ in structure from the British Harvest Mouse. — Ed. 
