10 
MOLAE TEETH AND OTHER REMAINS OE MAMAIALIA. 
nmcb. larger and more pointed in the Siwalik form than in the living species ; the 
molars of both species agree in having only two fossettes on the worn-crown. 
The molars of M. sivalensis are distinguished from those of R. tichorliinm (Guv.), and 
of R, incUcus by the presence of only two in place of three fossettes on the worn-crown 
and by the absence of the combing-plate. They resemble those of R. siimatrensis in 
having a large buttress at the antero-external angle ; the median collis is, however, 
much smaller in proportion to the anterior collis in the fossil than in the living 
species, and the latter lacks the large cingulum which occurs on the anterior sur- 
face of the teeth of the former species. 
Erom the molars of R. leptorliinus and R. hemitmcJius the very prominent 
buttress at the antero-external angle, the absence of the combing-plate, and the 
curved dorsum of the molars of the present species are sufficient distinctions. 
The molars of R. etniscus (“ Eal. : Pal. Mem.^ Vol. II, ylate 25, jig. 7) some- 
what resemble those of R. sivalensis, both having a buttress at the antero-external 
angle, a long cingulum on the anterior surface, unequal colles, a simple pointed 
crochet, no combing-plate, and presenting only two fossettes on the worn-crown 
surface. The molars of R. sivalensis are, however, distinguished by the posterior 
collis being more distinct and elongated, by the inner extremity of the median valley 
being three-cornered instead of oblong, by the crown being relatively longer in 
proportion to its width, and by the ridges of the buttress being placed farther apart, 
and extending lower down on the surface of the crown. 
The persistent dentition of this species seems to be as follows : — 
I 0 (P)-0 (?*) p 0-0 p 4-4 3-3 
0—0 '^•0—0 3—3 3—3 
Eigures of very much worn lower molars of this species are given in plate 75 
of the “ Eauna Antiqua Sivalensis.” The specimen figured here {plate 6, Jig. 1) 
is the last molar of the left ramus of the mandible ; the crown is in an early state 
of wear. Ths anterior collis {extreme left of figure) is remarkable for its very 
small size ; its inner boundary not extending beyond the middle line of the crown ; 
the anterior valley {left of figure) is narrower and shallower than the posterior valley 
{right of figure), and extends farther on the outer side ; the worn dentine-surface of 
the median collis {centre of figure) runs nearly at right angles to the antero- 
posterior axis of the tooth, while that of the posterior collis is placed very obliquely 
to the same axis. The posterior surface of the tooth is divided by a deep and 
nearly vertical groove ; on the inner side of this groove there is a very small conical 
tubercle ; there is no cingulum on any part of the tooth ; the enamel is smooth and 
polished and of uniform thickness. Owing to its shallowness the anterior valley 
becomes obliterated at an earlier period of wear than the posterior valley. The 
length of the specimen is 2’4s inches, and its width 1*4 inches. 
Erom Ealconer’s figure the species seems never to have developed the first 
premolar in the lower jaw ; the second premolar is of relatively large size. The 
( 28 ) 
