213 



The mandibles appear to be indistinguishable from Fal- 

 coner's type mandible of S. erythrogenoides, figured in the 

 ' Palaeontological Memoirs,' vol. ii. pi. xxxv. figs. 1, 2, 3; 

 the space occupied by the three true molars being pre- 

 cisely the same in both (0,010). Nehring 1 considers 

 S. erythrogenoides very close to S. eversmanni, Brandt 

 (S. altaicus, Eversmann). - The molars of the Erith cranium 

 seem indeed indistinguishable from some upper teeth from 

 the Forest-bed, figured by E. T. Newton in the Geol. Mag. 

 dec. 2, vol. ix. pi. ii. (1882), and provisionally referred to 

 that species ; but the three lower molars of the Forest- 

 bed form measure only 0,085 ; and the recent mandible 

 of S. eversmanni figured by Falconer (loc. cit. figs. 6, 7) 

 is decidedly smaller than the Erith specimens, and rela- 

 tively lower at pm. 4. On the whole, apart from the 

 question as to the specific distinctness of S. erythrogenoides, 

 it appears highly probable that the Erith Souslik belongs 

 to that form. Presented by R. W. Cheadle, Esq., 1876. 



Genus PLESIARCTOMYS, Bravard 2 . 

 The molars of this genus approach those of the Squirrels. 



Plesiarctomys gervaisi, Bravard 3 . 

 Syn. Sciurus arctomynus, Pomel 4 . 

 Hob. France. 



27584. Part of the left ramus of the mandible, showing the four 



{Fig.) cheek-teeth ; from the Upper Eocene of Apt (Vaucluse), 



France. This specimen, which is the type, is figured and 



described by P. Gervais in the Zool. et Pal. Frangaises, 



2nd ed. pp. 24, 25, pi. xlvi. fig. 13. 



Bravard Collection. Purchased, 1852. 



Genus ARCTOMYS, Schreber 5 . 

 Dentition : I. }-, C. jj, Pm. \ , M. |. 



1 Neues Jahrb. 1880, vol. ii. p. 121. 



2 In P. Gervais's Zool. et Pal. Fra^aises, 1st ed., explanation of pi. xlvi. 

 p. 2 (1848-52). 



3 Ibid. 



4 Catalogue Metkodique, p. 18 (1853). 



5 Saugethiere, vol. iv. p. 721 (1792), 



