Br. C. I. Forsyth Major— Rodents of W. Mediterranean. 503 



II. Bhagamys orihodon (Hensel), Murine Bodent from the Pleistocene 

 of Sardinia, Corsica, and Tavolara. 



Ehagamys orthodon (Hensel). 



Mus orthodon, Hensel, Zeitschr. deutsch. gaol. Ges., vol. viii, pp. 281-289, pi. xiii, 

 figs. 6-10 (1856) ; Forsyth Major, Atti Soc. Tosc. Sc. Nat., Proc. Verb., 

 Tol. iv, pp. 139-145 (1884) ; Trouessart, Cat. Mammalium, p. 477 

 (1898-99) ; Barrett-Hamilton, Proc. Zool. Soc. London, 1900, pp. 421, 422. 



In an appendix to his valuable paper " On geographical and indi- 

 vidual variation in Mus sylvaticus and its Allies," Major Barrett- 

 Hamilton has a note on Mus orihodon, which opens with the sentence 

 here reported : " In dealing with Mus sylvaticus, I must allude also 

 to Mus orthodon, which is believed to be very closely allied to it" 

 (italics mine), "and the skulls and teeth of which in the British 

 Museum collection I have examined."^ From his synonymy, where 

 we read " (aff. Iluri sylvatico, fide C. I. Forsyth Major, P.-verb. 

 Soc. Tosc, 1888, p. 129)," it results that I am supposed to 

 be the believer in the very close relation of the fossil with Mus 

 sylvaticus. The writer assumes the easy task to show from my own 

 specimens that this very close relation does not exist. The " aff. 

 Muri sylvatico . . . " is taken from Trouessart's Catalogue. 

 Neither of my two friends has taken the trouble to understand my 

 detailed description (in Italian) of the fossil in question. 



In the original description of Mus orthodon, Hensel had arrived at 

 the conclusion that his group of the Batten {Mus decumanus, 

 M. rattus, M. muscuhis) is in some respects intermediate between the 

 fossil and his group of the Mause (Mus sylvaticus, M. ayrarius, 

 M. minutus) ."^ With more material at my disposal, I was able to 

 show that some of the supposed differences of Mus orthodon from 

 the group Mause did not exist, so that, on a comparison of the 

 fossil with the two groups of European species of Mus, it is with the 

 group comprising Mus sylvaticus, M. agrarius, and M. minutus that 

 M. orthodon has the greater affinities. It agrees with this group in 

 the following points : — 



(1) Presence of a postero-internal cusp (c" of Hensel's diagram) 

 in the upper molars.^ 



(2) In mi having a greater number of cusps than in the group 

 Batten, in which latter the odd anterior cusp is always missing.* 



(3) In the pattern of the worn teeth, and 



(4) In the number and position of their roots the fossil is likewise 

 more related to the group Mduse.^ 



The peculiar characters of the fossil are clearly proved : — 



(1) From my lengthened description of the pattern of the molars. 



(2) From their hypselodonty.'^ 



1 Op. cit., p. 421. 



2 Op. cit., p. 289. 



3 Op. cit., p. 44. 

 * Ibid. 



^ Op. cit., pp. 44, 45. 

 6 Op. cit., p. 145. 



