CIIALICOTHEEIUM SIVALENSE. 215 



by the opening of the bisecting transverse valley, which ex- 

 pands in the centre of the tooth into a deep and very open 

 irregular fissure having a triangular bottom. 



The conical tubercle is situated at the inner side, as in 

 Anoplotherium, and forms a large projecting lobe arising from 

 a broad disconnected circular base. The side towards the 

 palate is nearly vertical ; the apex is compressed mto a sharp 

 convex edge, sloj^ing off towards the centre of the tooth. It 

 stands opposed to the anterior outer pyramid, an angular 

 gap intervening. A low ridge forming the inner margin of 

 the crown descends from its base, connecting it with the 

 posterior inner pyramid and subtending the opening of the 

 transverse bisecting valley. A similar ridge from the an- 

 terior side of the base connects it with a small front lobe to 

 be next noticed. These connecting ridges are wanting in 

 Anoplotherium ; they continue intact during advanced wear, as 

 arcuate enamel cornua appended to the disc of the tubercle. 

 In consequence of its isolated position, the conical tubercle 

 remains long unconfounded with the confluent discs of the 

 other lobes ; the apex is first abraded obliquely on the side 

 next the axis of the tooth ; it then wears down to a dej)ressed 

 disc of ivory encircled by a ring of enamel, and it remains in 

 this state when the other coronal eminences are ground 

 down to a common field ; while in Anoplotherium it is lost at 

 a much earlier period. 



Up to this point the accordance of Chalicotherium Sivalense 

 with Anoplotherium commune is complete, in the general re- 

 presentation of the coronal lobes of the back molars. But in 

 Anoplotherium, corresponding with the anterior outer hillock 

 there is an interior smaller lobe in front of it, separated by 

 a distinct furrow, the two forming, like the posterior lobes, 

 an opposed anterior pair. This lobe, which represents the 

 anterior inner crescent of the symmetrical molars of the 

 ruminants, is less developed in Anoplotherium than the other 

 lobes, and during wear it does not present more than an 

 oblong disc, corresponding with the anterior horn of the 

 ordmary crescent. This reduction in form is accompanied 

 by an excessive development of the fifth coronal eminence, or 

 ' conical tubercle,' which in the allied genera ordinarily 

 forms only a slender pillar at the opening of the transverse 

 middle valley. The deviation from the typical symmetry of 

 the ruminants first visible in Anoplotherium is carried out still 

 further in Chalicotherium, the anterior inner lobe being still 

 more reduced, while the conical tubercle is proportionally still 

 more developed. The exact determination of this point in 

 the fossil is of great interest, as the symmetry or otherwise 

 of this part of the molars usually bears an important relation 



