RHINOCEROS HEMITCECHUS. 335 



is confluent with and undistinguishable from the outer colline, 

 except by the offset of the crochet, and by the round or 

 barrel-shaped termination at the posterior inner angle. Not 

 a vestige even remains of the posterior outer angle. In fact, 

 the hind leg of the V is composed along two-thirds of its 

 length of the outer colline, the remaining third being made 

 up of the posterior transverse colline, with no mark of de- 

 marcation between them. No trace of a depression or groove, 

 corresponding with the posterior fossette, is left upon the 

 surface of the enamel. These characters are well shown by 

 the accompanying figures in PL XVIII. fig. 7, representing 

 the summit of the crown in plan, and fig. 6, the same from 

 the inner side, in a germ of the last true molar, left upper, of 

 Bhin. bieomis, drawn two-thirds of the natural size : (a) indi- 

 cates the anterior colline; (b), the longitudinal colline; (c), 

 the continuation of the latter, which is the homologue of 

 the posterior transverse colline ; (d), the crochet ; (e), the 

 anterior barrel; (/), the anterior basal bourrelet; {g), the 

 posterior barrel ; (h), a small tubercle at the posterior inner 

 angle ; and (i), the vertical groove of the anterior outer angle. 



Let us now examine this tooth as it occurs in Bhin. hemi- 

 toechus. Figs. 3 and 4 of PL XVII. represent top and side 

 views of three-fourths of the natural size of an intact germ of 

 the left last molar, corresponding with the figs. 7 and 6 of PL 

 XVIII. of Bhin. bieomis ; and fig. 5, PL XVIL, gives an erect 

 view of the outer surface. The same letters of indication 

 apply to the different parts. The outline of the crown in 

 plan is triangular, exactly as in the Bhin. bieomis ; and the 

 ridges (a and b) meet at an acute angle, yielding the same 

 V-shaped pattern, the outer and the posterior ridges (b and c) 

 being continued in the same line without interruption ; the 

 anterior basal bourrelet (/) repeats the form presented in fig. 

 7, PL XVIII. , but is more salient. The crochet (d) is pro- 

 jected farther forwards across the valley, and when the erect 

 figure, PL XVIL fig. 4, is compared with PL XVIII. fig. 6, it 

 is apparent that ha the former the crochet makes a more 

 acute angle with the posterior barrel. The niche of the 

 anterior outer angle (a) is more pronounced, and there is 

 an intercolumnar tubercle (h) at the mouth of the valley 

 which is not seen in the African species. This tubercle is 

 also present in m. 3 of fig. 2, PL XVI., and strongly de- 

 veloped in the detached specimen, fig. 5, PL XVIII. , but 

 wanting in m. 3 of fig. 1, PL XVI. On the whole there is 

 a very strong general agreement in form between the last 

 true molars of Bhin. bieomis and Bhin. hemitcechus ; the 

 most obvious difference being the considerably greater di- 

 mensions of the tooth in the latter. 



The transverse valley in Bhin. hemitcechus is triangular at 



