MURID&. 209 
RODENTIA. MURID. 
yg. 79. 
PLO ‘ SES —~ 
/ 7 e, Y-y—)| San pss <; fi Lo > : 
Sere eee SOON 
Kirkdale, Nat. size. a, 6, molars magnified. 
MUS MUSCULUS. (?) Mouse. 
Mouse, Buckanp, Reliquie Diluviane, pp. 19, 265, pl. 11, 
figs. 7, 8, 9. 
Rat des Cavernes, Cuvier, Ossemens Fossiles, tom. v., pt. i. p. 55. 
Mus musculus fossilis, Karo, Denkschriften der Vaterland : Gesellschaft 
der Aerzte und Naturf. 8vo. Schwabens. 
Most unequivocal evidence of a species of true A/us has 
been yielded by the fossils from Kirkdale cavern, of which a 
lower jaw and teeth are figured in the ‘ Reliquie Diluviane.’ 
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 A/urida, the 
oceasional 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 Ciningen ; in caves in the South of 
France,* and in Belgium.+ 
* Serres, Journal de Géol., ii1., p. 254. + Schmerling, loc. cit. 
Pp 
