216 FAIIN^A ANTIQUA SIVALENSIS. 



to the construction of the extremities as regards the number 

 of toes, thereby indicating the afSnities of the genus. 



The characters presented by the reduced inner lobe in 

 Chalicotherium Sivalense are these : — From the apes of the 

 anterior outer vertical bulge a low ridge proceeds across, 

 bounding the ' tooth in front ; it is concealed about the 

 middle of its course by the overlapping of the adjoining 

 tooth, but reappears near the inner thu-d of the distance, in 

 the form of a lovf' compressed tubercle, which, as above de- 

 scribed, is continued forwards m an enamel ridge, sweeping 

 round the base of the great conical lobe upon which it ter- 

 minates. This small tubercle represents the inner division 

 of the anterior pair in Anoplothermm. A well-marked ante- 

 rior transverse narrow valley, which remains distinct after 

 advanced wear, separates it from the corresponding and 

 opposed outer lobe, and also from the base of the conical 

 tubercle ; therefore, the anterior inner, or fourth symmetrical 

 lobe, which in Anoplotherium is reduced to one horn of the 

 ordinary crescent, is still more rudimentary in Chalicotlierium, 

 attaining little beyond the development of an anterior ' talon,' 

 while the conical tubercle, representing the fifth or odd 

 coronal lobe, is proportionally enlarged at the expense 

 of the reduced segment. There is no basal collar or ' bour- 

 relet ' upon this or any other part of the back molars of Cha- 

 licotherium Sivalense. 



The difference of pattern yielded by the grinding in face 

 during progressive wear is finely exhibited by the different 

 conditions of the three back molars (Plate XVII. fig. 1). The 

 last (m. 3) shows the germ form of the crown, the wear being- 

 limited to the posterior inner face of the anterior outer pyra- 

 mid. The penultimate (m. 2) shows the two outer and the pos- 

 terior inner lobe, half worn and confluent into a common 

 field of ivory, while the conical tubercle is almost intact. The 

 posterior fissm'e forms an open gap separated from the cen- 

 tral valley by a belt of ivory, as in the molars of Palceothe- 

 rium. The termination of the great transverse valley forms 

 a triangular depression in the middle of the tooth, while its 

 opening remains in the state presented by the germ. The 

 anterior valley still presents the condition of a transverse 

 fissure. The first true molar is considerably more advanced 

 in wear ; the united disc of the three pyramids is nearly flat ; 

 the posterior fissure is reduced to an oblong peninsular patch 

 of ' fossette ' of enamel ; the conical tubercle is ground down 

 to an isolated anniilar depression, with a divergent enamel 

 ridge at either side ; the transverse middle valley forms two 

 triangular depressions luiited by a narrow neck ; and the an- 

 terior transverse valley is reduced to two enamel pits, the 



