276 MAMMALS. 



Reithrodons of the North Americau type, one of them a North American species ; one Sigmodon, 

 also North American ; and a new species of the North American genus of Rats, Neotoma. Other 

 similarly allied species of Squirrels, &c. were also met with. 



Old-world Rats and Mice (Mus). An immense number of these have been described, and 

 a careful revision of them is much needed. In the purged list which I have given in the Appendix, 

 it will be seen that there are still ninety-three species reckoned good, while sixty-six have been 

 disallowed as synonymes. Dr. Giebel, who is more trenchant, admits only thirty-three species as 

 distinct, but after absorbing upwards of thirty names of described species as synonymes, he records 

 forty-five other supposed species, the descriptions of which are so insufficient that he has been 

 unable to decipher them, or to express any opinion upon them. 



Out of this large number there are four species which are almost cosmopolitan. Originally, 

 undoubtedly, from the Old World, they now inhabit every quarter of the globe ; the Conmion 

 Mouse, the Brown Rat, the Black Rat, and the Mus tectorum, or Egyptian Rat. Whence they 

 have respectively sprung is involved in obscurity. 



The Common Mouse may perhaps not be so completely cosmopolitan as is generally supposed. 

 Mr. Blyth remarks that he has never seen an Indian specimen. It appears, like the Rats, to vary 

 under altered conditions of life, the specimens in Guatemala, for example, being smaller than usual. 



The Brown Rat, judging by its English names, last came from Norway or Hanover, it being 

 generally Icnown as the Norway or the Hanoverian Rat. The latter, however, was a political name, 

 or name of prejudice, used by Old Jacobites, to signify that all ill things came in with the 

 Hanoverian Succession. But both names are equally erroneous ; and the commonly received 

 opinion tliat the sj^ecies originally came from the centre of Asia, — that ierra incognita to which 

 man, when puzzled, has had recourse for the original site of many species, must, according to 

 mj' view, be not far from the right one ; to the south of Northern Asia I look for almost the entire 

 re-peopling of Eurofie after the glacial ciDoch. It was Pallas who first gave currency to the notion that 

 the Brown Rat also came from that quarter. According to him it belonged originallj' to the wanner 

 regions of Central Asia, — more especially Persia, which rather refractorily happens to be one of the 

 very few places where the Rat in question is not to be found. Capt. Hutton, in 1846, states that 

 " house rats are unknown in Kandahar ; " and Mr. Blyth* mentions, that in India it is chiefly 

 observed about the ports, a significant enough indication whence it came there — Schrenckf also 

 informs us that it is not known in Siberia, though frequent in China, Japan, and Amourland, into 

 which it ajjpcars to have penetrated from the coast. A good proof of the recent introduction of the 

 Rat into Europe, were one needed, is furnished by the fact that neither the ancient Greeks nor 

 Romans had a name for it. As with potatoes and other novelties, not knowing the thing they 

 could not name it. The Mouse is the only species that they seem to have known, and even 

 it seems not to have been very common, for when the Emperor Heliogabalus got up a mouse-show in 

 Rome, all that he mustered was about ten thousand. J There would be little dif&culty in collecting ten 

 millions now-a-days. Pallas gives no very ancient date for the advent of the Browm Rat into Europe. 

 He says it crossed the Volga from Central Asia in large troops in 1737, peopled Russia, and subse- 

 quently spread over the whole of Europe. According to Erxleben it reached England in 1730, France in 

 17'j0, which, looking to PaUas's date, seems all in harmony', rightly reasoned and in his own division, 



* Blyth, " Catalogue," p. 113. 1690, p. 110, as quoted in Marsh, G. P., "Man and Nature 



t ScHRENCK, "Mammals of Amourland." or Physical Geography as modified by Human Action," 



J LAMrRiDins, " Hist. Aug. Scriptores," cd. Casaubon, 18G4, p. 80. 



