308 AMERICAN WHITE-FOOTED MOUSE. 



and after an examination of many hundred specimens, been induced to 

 set it down as a variety only. 



We have adopted the name given to it by RAPiNEsanE, in deference 

 to the opinions of Richardson who supposed that it applied to this species, 

 Richardson himself, however, — not RAFiNEsauE, gave a true description 

 of it. 



GoDMAN, in describ'ng Mus agrarius, we feel confident, had reference 

 to this species. He had, however,-never seen the European Mas agra- 

 rius of Pallas, else he would not have made so great a mistake ; we 

 have on several occasions in Denmark and Germany compared them, 

 and found that they scarcely bear any resemblance to each other. Mas 

 agrarius has a short tail and short hairy ears. Fokstee, and Harlan, 

 refer this species to Mus sylvaticus of Europe. Forster's specimens came 

 from Hudson's Bay at an early period, when it was customary to consider 

 American species of Quadrupeds and Birds as mere varieties of those of 

 Europe. Harlan instead of describing from an American specimen, 

 literally translated Desmarest's description of the European Mus syl- 

 vaticus and applied it to our species, (see Mam. p. rOl,) in doing which 

 by neglecting to institute a comparison he committed a great error. 



We were favoured with the privilege of comparing specimens of Mus 

 sylvaticus and M. leucopus, through the kindness of Prof. Lichtenstein at 

 the Berlin museum. Although there is a general resemblance, a mo- 

 ment's examination will enable the naturalist to discover sufficient 

 marks of difference to induce him to separate the species. Mus leucopus 

 has a little longer tail. Its ears are longer, but not so broad. The under 

 surface of the tail of Mus sylvaticus is less w^hite, and the white on the 

 under surface of the body does not extend as high on the sides, nor is 

 there any distinct line of separation between the colours of the back and 

 under surface, which is a striking characteristic in the American species. 

 But they may always be distinguished from each other at a glance by 

 the following mark : in more than twenty specimens we examined of 

 Mus sylvaticus we have always found a yellowish line edged with dark- 

 brown, on the breast. In many hundred specimens of Mus leucopus 

 we have without a single exception found this yellow line entirely want- 

 ing, all of them being pure white on the breast, as well as on the whole 

 under surface. We have no hesitation in pronouncing the species 

 distinct. 



