British Fossil Species of ApoJemus. 581 



collection of Mr. G. White. It comprises the greater part 

 of a left maxilla with ^ in place, a number of detached 

 teeth, including examples of !^, 5"^, ^n? a"<-l the upper and 

 lower incisor. 



The teeth are quite similar in form and size to those of 

 A. si/lvaticus ; in ?H:^ cusps 1 and x' (see Barrett-Hamilton 

 and Hintoii, 'British Mammals,' ii. pi. xxviii.) are normally 

 develop! d. 



In tlie maxillfiry fragment the lower portion of the root of 

 the zygoma is present, and the palatal surface, from the 

 hijider margin ot the incisive foramen to the maxillo-palatine 

 suture, is complete. The latter suture is deeply digitated, 

 and extends as far forwards as the antero-internal cusp {x') 

 of '-^, instead of being situated opposite the hinder part of 

 this tooth or the front part of ?^, as in recent sylvaticus. 

 1'he posterior margin of the incisive foramen is placed 

 slightly, but distinctly, in front of instead of level with the 

 anterior root of 51:i. These two small characters distinguish 

 the fossil from all the many skulls of sylvaticus which I have 

 examined, and they serve to show that one cannot assert the 

 fossil to be identical with any living member of the group. 

 It is, therefore, proposed to regard the High Terrace form as 

 a distinct species, for which the name A. wliitei is used. 

 Having regard to the faunistic agreement which subsists 

 between the High Terrace Drift and the Forest Bed, it is by 

 no means improbable that the fossils from the latter horizon 

 will prove later on to be referable to A. lohitei also. 



3. j\l iDDLE Pleistocene. 



Apodemus sp. 



Mns sylvatims, Ilinton & Kennard, Essex Naturalist, vol. xi. p. 347 

 (1900). 



Horizon. The Middle Terrace Drift of the Thames at 

 Grays Thurrock, Essex. 



From this deposit numerous detached teeth and a fragment 

 of a right ramus were obtained by Mr. J. P. Johnson and 

 Mr. G. White. These remains agree in size and dental 

 pattern with A. sylvaticus, but they do not permit of precise 

 determination. 



■1. Late Pleistocene. 

 (a) Apodemus sylvaticus, L. 

 A large number of remains, indistinguishable in size or 



