EODENTIA. 53 



A variety of A. arvalis is represented in the Forest-bed by- 

 certain teeth which approach those of A: nivalis, Martin. 



Possibly ihe forms named Arvicola campestris by Messrs. R. 

 and A. Bell (Proc. Geol. Assoc, Vol. II., p. 212, 1872) in their 

 Kst of Upper Crag Mammals may have belonged to the present 

 species ; but I have been unable to get any clue to the specimens, 

 and the only remains oi Arvicola I have seen from the Norwich 

 Crag belong to Arvicola intermedins. 



The species has also been found in the Pleistocene, and is now 

 living on the continent of Europe. 



MiCROTus (Arvicola) gregalts, pallas. 



(Vert. Forest Bed, p. 90, Plate XIV., Figs. 6, 6a.) 



Teeth which are believed to belong to this species have been 

 found in the Forest-bed at West Ilunton. At the present day 

 A. gregalis is an inhabitant of Eastern Siberia. 



MicEOTTJS (Arvicola) glakkolus, bcbheber. 



{Bank Vole.) 



(Vert. Forest Bed, p. 82, Plate XIV., Figs, l-lc.) 



This species is first given as occurring in the Forest-bed by 

 Messrs. Blackmore and Alston (Proc. Zool. Soc, 1874, p. 461). 

 It is doubtful whether the specimens so named, which are in 

 the Norwich Museum, really belong to A. glareolus, but for- 

 tunately an undoubted example has been found in the Forest- 

 bed at West Eunton. 



The species occurs in Pleistocene deposits, and is now living 

 throughout Europe north of the Apennines and east of the Ural 

 Mountains. 



MiCROTUs (Arvicola) intermedius, nbwton. 



(Vert. Forest Bed, p. 83, Plate XIII., Figs. 1-13.) 



This species was founded for the retention of numerous speci- 

 mens of Arvicola from the Forest-bed and Norwich Crag. 

 (Mem. Geol. Surv., Vert. Forest Bed, p. 83, 1882) which differed 

 from A. amphibius in having well developed fangs to the cheek 

 teeth, and in being of a somewhat smaller size. It is no doubt 

 the form alluded to by Sir K. Owen (Brit. Foss. Mamm., p. 205) 

 as intermediate in size between the Water-vole and Field-vole. At 

 present the species is only known with certainty from the Forest- 

 bed of Norfolk and Suffolk, and from the Norwich Crag of 

 several localities in Norfolk, but an Arvicola with fanged teeth 



