RODEXTIA. j 13 



Tbe Black Rat (Jf. rathu, Lin.), which the ancients hare not alluded to, and which appears to have enter* i 



Europe during the middle ages. It is more than double toe size of the Mouse in all its dimei - . i be fur is 



blackish [with the cars 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 bj M. F. Cuvier aa the Surmul 



The Brown Rat, or Surmulot (.'/. decumamu, 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 

 belons to Persia, where it lives in burrows : it was not till 1727, that, alter an earthquake, it arrived at Astracau, 

 by swimming across tbe Volga. 



It would seem that the Black Rat, also, originated in the East ; and these two large species, together with the 

 Mouse, have been transported in ships to all parts of the globe. 



[Of the very numerous others, it must suffice to name the huge Bandicoot Rat of India (.V. giganteui, 



Hardw.), which is much larger than the Surmulot. Those indigenous to South America have D I implicated 



folds of enamel to their molars.*] Some have spines mingled with their fur, as 



The Cairo Mouse (Jf. caMtimu, Geoff.), which has spines en the hack in place of hairs, and was noticed by 

 Aristotle. 



[Only two strictly indigenous British .Mice have hitherto been described: the first, extremely diminutive, is the 

 Harvest Mouse (Jf. messoritu, Shaw), with short ears, and red fur similar to that of the Common Dormouse: it 

 constructs a beautiful round or pear-shaped not, attached to corn-stems, or p'aced in low hushes ; and is remark- 

 able for its tail being sliirhtly prehensile at the extremity. The second is commonly termed the Long-tailed Field 

 Mouse (.1/. tylvalictut), and might almost form a separate subgenus; it rather exceeds the common Mouse 

 in size, with proportionately larger ears, and much largerand 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 Han est Mouse, and never 

 enters buildings, where the other is often carried with the sheaves.] 



Warm climates produce Rats, similar in every detail to those of which we have just spoken, except 

 that their tails are more hairy. Such are 



Hypudtetu variegattu, Licht., var. flava ,• Mertonet tymetuit, Id. To which must be added the Arvieola 

 mettor, Le Conte; An. horteruii, Harl., or Sygmodon, Say, distinguished however by its hairy ears, like 

 the Otomyt. 



Am up, also with a hairy tail, but the teetli of which wear away faster, comprises the Hypudtetu oberus, 



Licht., the Mus rufieaudus, Id., and also the Meriones tericetu of the same naturalist, characterized by the 

 projecting ridges Of the molars, which alternately catch in each other. 



We have then to group the tieotoma floridanum of Say, or the Arvieola floridana of Harlan, and the Anient 

 gottyphia, Le Conte, tw o species which, size excepted, are very similar even in their colours, anil the molars of 

 which, provided with roots [after a while], when worn a little, have crowns s.milar to those of the ArvieoUe. [The 

 tail in one of them is covered with hair of tolerable length. Both inhabit North America. 



Reitkrodon, Waterh., requires also to be introduced here, distinguished by its groo\ i d upper incisors, its arched 

 and Rabbit-like head, great eyes, and large and round ears. Three or four species are known, from Soc'.h 

 America, where they were discovered by Mr. Darwin. 



The Pseuilonii/s 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 

 species, Ps. austnilis, inhabits holes in swampy places, at Liverpool plains. 



It is necessary also to introduce' here the liu/ni/otis nlbipet, Licht.; Conilurus ronstrirtiix, Ogilby; another 

 rodent from New Holland, the si/.e of a Rat, with delicate ample cars, and a long, hairy, and somewhat tufted tad. 

 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.] 



Tin. Gkrbils {Gerbillits, Desni. ; Meriones, Illig.) — 

 Have molars scarcely differing from those of the Rats, merely becoming sooner worn, so as to form 

 transverse ridges. Their upper incisors are furrowed with a groove; their hind feet arc somewhat 

 longer in proportion than those of Rats in general, with the thumb and little toe but slight!] sepa- 

 rated : their tail is [very] long and hairy, [and generally tufted]. 



The sandy and warm parts of the eastern continent produce several species, [mostly of a light bull' colour, white 

 underneath]. 



Tmk Merions {Meriones, 1'. Cuv.), — 



Which we separate from the Gerbils, have the hind feet still longer, the tail nearly naked, and a \er\ 



small tooth before the superior molars j characters which approximate them to the Jerboas: their 

 superior incisors are grooved, as in the Gerbils, and their toes also are similar. 

 There is a small species In North America, Mus canadensis, Pen.', Dipus canadensis, Shaw j l>. amerleamms, 



• Cm F then, the upper lip of which li icu Uric*, which i w.rir 



( i , ■,. UvloeUlui, Brandt. Then ui ilso mi »rbur<nl Ml e la diffi i In itruetnrt boa iht Brltiih ll«r>c.i H 



