258 E. T.Newton — Pre- Glacial Manunalia. 



am inclined to think that raost of the remains referred to as Castor 

 were really Trogontherium. However, quite recently two or three 

 undoubted examples have been found at West Runton and Kessing- 

 land, so that there is no question as to the occurrence of this genus 

 in the " Foi'est Bed Series." I have preferred to retain Prof. Owen's 

 name of Castor Enropcsus, seeing that good authorities acknowledge 

 a constant, though slight, difference between this form and the 

 American Beaver. 



Arvicola. — The remains of Voles were recognized among the 

 " Forest Bed" Mammalia as early as the year 1840 (Lyell, Lond. Edin. 

 Phil. Mag. sei\ 3, vol. xvi. p. 345). Prof Owen seems to have been 

 the first to refer any of them to the Arvicola amphibia (Brit. Foss. 

 Mams. 1846, p. 205); and since then it has been included in most of 

 the lists. Within the last few years remains of a smaller species 

 have been found, and these have been referred by different writers to 

 the species given in the list above. After a careful examination of 

 a large series of Voles' remains, including, as I believe, all the im- 

 portant specimens hitherto found, I am led to the following con- 

 clusions : 1st. That of the larger forms of Vole found in the 

 " Forest Bed," the greater number have well-developed fangs to 

 the cheek teeth, in the adult condition, and on this account they 

 cannot be referred to the common Vole, although the patterns of the 

 teeth are almost identical in the two. I propose therefore to call 

 this species Arvicola {Evotomys, Coues) intermedia, in reference to 

 the intermediate position which it occupies between the Arvicola 

 amphibia and Arvicola (Evotomys) glareola. 2nd. That it is 

 doubtful whether the true Arvicola amphibia really occurs in the 

 " Forest Bed." All the examples in the Green Collection which are 

 referable to this species are from Ostend, and it is just possible that 

 they were obtained from an alluvial deposit which is known to 

 exist in the neighbourhood. Some few large specimens of teeth 

 from West Eunton have no fangs, and may possibly be A. amphibia, 

 but the evidence is far from conclusive, and it seems best to put a 

 query after the species. 3rd. That most of the smaller Voles are to 

 be referred to A. arvalis, seeing that no example of the characteristic 

 second upper tooth of ^. agrestis has yet been obtained, while several 

 examples of upper teeth with five angles have been found. 4th. One 

 small lower jaw with fanged teeth, and several small teeth also with 

 fangs, are definite evidence of the occurrence of Arvicola [Evotomys) 

 glareola. Limb-bones of the larger and smaller species are also 

 known. 



Mus. — In the year 1869, Prof. Boyd Dawkins gave the Mtis 

 musculns as occurring in the Pre-Glacial Forest Bed (Quart. Journ. 

 Geol. Soc. vol. XXV. p. 198), but there seems to have been some 

 mistake about this specimen, as it has been omitted from each of the 

 lists which he has published since that date. However, we are now 

 in a position to re-insert the genus, although with a different species ; 

 for Messrs. C. Reid and A. Savin have each obtained a portion of 

 a lower jaw with teeth, and both these agree precisely with the 

 recent Mas sylvaticus both in size and in the arrangement of their 



