209 



RODENTIA. MURIDJE. 



Kirkdalc, Nat. size, a, b, molars magnified. 



MUS MTJSCULUS. (?) Mouse. 



Mouse, BUCKLAND, Reliquiae Diluvianse, pp. 19, 265, pi. 11, 



figs. 7, 8, 9. 



Rat des Caverncs, CUVIER, Ossemens Fossiles, torn, v., pt. i. p. 55. 



Mus musculus fossilis, KARG, Denkschriften der Vaterland : Gesellschaft 



der Aerzte und Naturf. 8vo. Schwabens. 



MOST unequivocal evidence of a species of true Mus has 

 been yielded by the fossils from Kirkdale cavern, of which a 

 lower jaw and teeth are figured in the ' Reliquiae Diluvianse." 1 

 Instead of the molars being rootless, and with deeply- 

 inflected plates of enamel, a structure which approximates 

 our so-called Water-rats and Field-mice to the Beaver, 

 the true Rats and Mice have the crowns of the molars 

 simply tuberculate, with the enamel bent into slight de- 

 pressions on the grinding surface, and the crown is always 

 supported by well-developed roots : this more simple form 

 of tooth governs the mixed diet of the true Murida-, the 

 occasional carnivorous habits of which are well known. 

 The fossil specimens of this genus differ from the common 

 Mouse only by a slight superiority of size. 



Fossil remains of species of Mus have been found in the 

 tertiary beds at CEningen ; in caves in the South of 

 France,* and in Belgium. -f- 



* Serres, Journal de Geol., iii., p. 254. t Schmerling, loc. cit. 



P 



