198 MR. E. T. NEWTON ON THE VERTEBRATE [May 1 894, 



M. ratticeps, for which it may easily be mistaken ; but in M. ratticeps 

 the front prism of this cheek-tooth is continuous with the fourth inner 

 prism, and is not shut off from it by the enamel fold, as it is in the 

 present species. There are portions of four skulls which may belong 

 to this species or to M. ratticeps, the posterior cheek-tooth having 

 4 inner and 4 outer angles. Microtus gregalis has been found in the 

 Norfolk Forest Bed and in Pleistocene deposits on the Continent. 

 It is now living in the treeless regions of Siberia, east of the Eiver 

 Obi. 



Limb-bones of small Rodents. — In addition to the skulls and lower 

 jaws of small rodents above noticed, numerous limb-bones have been 

 met with ; but, while the jaws with teeth can be referred to the 

 genera and species given above, there is much difficulty in correlating 

 the other bones with them. The limb-bones, especially the femora 

 and -humeri, may be separated according to their sizes and propor- 

 tionate robustness into about a dozen groups. The largest of these 

 bones agree satisfactorily with Microtus amphibius ; but few, if any, 

 of the others present a sufficiently close agreement with such recent 

 forms as I have been able to compare them with, to render a 

 reference certain. In many cases the fossil bones which seem 

 most nearly to resemble any particular living species are found to 

 be not only stouter, but to have proportionately larger heads. At 

 present, therefore, many of the limb-bones have not been specifically 

 determined. 



Ungulata. 



Eleplias primigenius? (Mammoth.) — The only evidence of the 

 Elephant in the Ightham fissure is supplied by one of the smaller 

 bones of the tarsus, a well-preserved third cuneiform bone of the left 

 side, and possibly by some pieces of large ribs. There is no doubt 

 as to the foot-bone belonging to Elephas, and so little as to its being 

 Mammoth that I have placed it in this species. There is some 

 doubt as to whether the Mammoth occurs in the Forest Bed. 



Equus caballus. (Horse.) — Portions of two scapulas, a piece of 

 femur showing the third trochanter, a first digital phalange, and a 

 splint-bone of a good-sized horse are referred to this species, the 

 Pleistocene form being now recognized as at most a variety of the 

 recent E. caballus. An ungual and one other phalange of a much 

 smaller horse have also been found. The domestic horse is almost 

 certainly identical with the form found so abundantly in Caves and 

 Pleistocene river-deposits, and extends back in time at least as far 

 as the Forest Bed. 



Rhinoceros antiquitatis. (Woolly Bhinoceros.) PI. XL figs. 13— 

 ] 5. — Four well-preserved milk-teeth of this species have been found ; 

 they are the first, third, and fourth deciduous molars of the left upper 

 jaw, and the third deciduous molar of the right lower jaw. The 

 upper teeth possess the completely separated median accessory valley 



