TEETH OF RHINOCEROS FROM ILFORD. 233 



papers by himself and Mr. J. P. Johnson which have appeared 

 in the Essex Naturalist. It is a detached fourth premolar of 

 the left upper jaw. The transverse valley is completely isolated 

 through wear and into it, from the posterior barrel, is projected 

 a strongly developed bifid crochet. The outer wall gives off two 

 very small combing plates, one of which is parallel to and just 

 above the bifid crochet. The other is given off in a line with the 

 anterior external angle of the tooth, converging towards the first 

 and the crochet at a right angle. The posterior valley is not yet 

 isolated, and the cap of enamel which arises from its inner wall, 

 and which passes over the hind barrel and so into the inner wall 

 of the tooth is still in great measure intact (fig. 2). There is a 

 well marked basal bourrelet passing right round the anterior 

 barrel. This starts from near the grinding surface a little 

 inwards from the anterior angle ; from this point it gradually 

 sinks until the inner extremity of the anterior barrel is reached, 

 from whence it rapidly rises up again ending off at the inner and 

 forward rim of the enamel cap before spoken of. The dimensions 

 of this tooth are : — 



Antero-posterior length measured along outer surface at base . . 17 inches 



,, inner ,, .. 125 ,, 



Antero-transverse width at base .. .. .. 247 ,, 



Postero- ,, ,, ., •• .. ..22 ',, 



Height of crown at junction of anterior and posterior barrels .. 1-4 



,, ,, anterior outer angle .. .. .. i'88 ,, 



I have referred this specimen to R. leptorhinus, Cuvier, 

 pro parte i=R. megarhinus, De Christol). The point to which I 

 wish to direct special attention is the remarkable state of wear 

 and the figure will give a much better idea of the characters 

 described here than any mere verbal description.- In all known 

 species of Rhinoceros, either fossil or recent, the small posterior 

 valley is the first to be isolated into a fossette by the detrition of 

 the tooth. This arises from the fact that while the entrance to 

 the posterior valley is comparatively shallow, not cutting deeply 

 into the body of the tooth, being from this cause soon obliterated, 

 the entrance to the transverse valley forms a much deeper cleft 

 separating the barrels and consequently remaining for a propor- 

 tionally longer period intact. But in this specimen it is the 

 transverse valley which has been isolated first, the posterior 

 valley having its entrance still intact thougli cutting into the 

 tooth no deeper than usual. This malformation appears to me 



