Quadrupeds, 7233 



tinguished from the new British rat, and I believed them to be identical, though the 

 West Indian rats average rather larger in size, and are more uniformly of a brown 

 colour. The cranial characters scarcely bear out this idea. In the British Museum, 

 among the stuffed British Mammalia, is a wretched specimen, wretchedly stuflFed, of 

 the new rat ; but it is incorrectly labelled Mus rattus, the name of the old English 

 black rat, with which I suspect it has long been confounded. The cranial characters 

 of the two are, however, very diflferent, and their differences are such as are not com- 

 patible with mere variety — they are specific. I may here mention that my paper on 

 the cranial characters of these two rats, with figures of the skulls, will probably appear 

 in an early number of the ' Proceedings of the Linnean Society.' About two years 

 since I presented three specimens of the new rat to the Zoological Society ; one of 

 them died, but the other two are still living in the Society's gardens, and may be found 

 in the small house for Mammalia not far from the fish house. The rats are in good 

 health, but accidents appear to have diminished the length of their tails, and their 

 ears are covered with warts. I cannot conclude this little communication without 

 expressing my belief that our knowledge of the British rats is very imperfect and not 

 a little confused. The different species breed together very freely, and the offspring 

 will breed with either of the parent species, resulting in endless gradations between 

 the two. The new rat breeds freely with the common brown rat {Mus decumanus), 

 and, where they mingle, every shade of difference between each species may be found. 

 We have in this country a black rat with a white chest, probably a variety of Mus rattus. 

 In the British Museum there are two stuffed rats (chestnut coloured with white breasts), 

 which were captured in Cambridgeshire, and which are either a distinct species or a 

 very singular variety. A distinguished Irish naturalist, the late Mr. Robert Ball, 

 believed there was still another species of rat in Ireland, which he named Mus Hiber- 

 nicus. The numerous readers of the ' Field ' might do much to clear up our uncer- 

 tainty about doubtful species or varieties, and any specimens of rats exhibiting 

 peculiarities or unusual appearances I should be very grateful for ; and I may add 

 that living specimens would be valued at the Zoological Gardens, Regent's Park. — 

 James Salter ; 1, Ploivden Buildings, Temple. 



[I reprint the preceding from the ' Field ' newspaper because of its value in a 

 Natural-History point of view, and having done so I cannot courteously omit to notice 

 Mr. Sailer's mention of my own name. My knowledge of Mr. Salter's still unpublished 

 communication I admit to have been very limited, and I accept very gladly his cor- 

 rections as to the name of the Society and the date of the reading. My statements and 

 suggestions about the rat, which are really the gist of the matter, seem corroborated 

 by Mr. Salter's interesting communication. A word, however, about the following 

 paragraph seems necessary. " If Mr. Newman were practically acquainted with the 

 difficulty of making out, with absolute certainty, the specific limits of these cosmopolitan 

 rodents, so subject to variety, sor^eady to cross breed, he would, I think, speak a little 

 more guardedly." Now I wish most distinctly to disclaim all idea of " making out 

 with absolute certainty the specific limits " of the members of the rat family. Often 

 as rats, black, white and brown, have been brought for me to decide the species, I have 

 always declined doing so, otherwise than in such vague terms as " I think it must be 

 the common brown rat.'' I have never expressed an authoritative opinion of my own, 

 or felt much confidence in the opinion of others. I have seen in the same litter of rats 

 individuals which appeared to be of the black, and others that appeared of the brown 

 species. This admixture of the two colours has been explained away by supposing the 



XVIII. 3 L 



