536 



RHINOCEROS. 



its commencement, as in the penultimate, m. 2 of fig. 1, PI. 

 XVI., and is then reduced to a narrow cleft by the projection 

 of the free end of the crochet close to the anterior barrel. 

 The continuation of the valley, beyond the crochet, forms an 

 oblong and somewhat angular expansion, rising from the 

 bottom of which a line of denticidar points is seen, con- 

 nected into a plate attached to the outer colline. This 

 ' combing plate ' is projected forwards parallel to the 

 crochet, repeating the pattern already described in p.m. 4, 

 m. 1, and m. 2 of fig. 1, and in m. 2 of fig. 3, PI. XVI. A 

 similar disposition of these denticular points is exhibited in 

 m. 3 of fig. 1 of PI. XVI. When the crown is ground down 

 by use, the effect is to produce the appearance presented by 

 m. 3 in fig. 2, PI. XVI. of a double crochet projected across 

 the valley, one of the processes representing the ordinary 

 crochet, and the other the ' combing plate.' The constancy 

 of this character in running through the whole of the molars 

 proves its importance as a mark of specific distinction. 



In some cases, the worn pattern of the middle valley is 

 still more complex. A fine example of this is presented by 

 the last true molar of the specimen No. 22,020 of the Pa- 

 lseontological Catalogue, British Museum, purchased of the 

 late Mr. Ball, and reported to have been procured from the 

 fluviatile deposits of the Valley of the Thames. The five 

 posterior molars of the right side are presented in sequence, 

 the last being in full wear ; and in this tooth, besides the 

 crochet and ' parallel combing plate,' the termination of the 

 middle valley presents two additional processes ; namely, a 

 stout plate projected at right angles to the crochet, from the 

 anterior outer angle, and a short plate emitted from the 

 anterior colline, above the crochet, and directed backwards. 

 The valley, in consequence, presents a pattern of extreme 

 complexity, with plates jutting into it from three sides. 1 



In Bhin. bicornis, PI. XVIII. fig. 7, the valley is of a similar 

 form, but its posterior wall is free from any combing plate, 

 or tendency to a double crochet. In Bhin. megarhinus the 

 crochet of the last molar is also single, and emitted at an 

 open angle from the posterior colline. In illustration, fig. 

 9 of De Ghristol's plate, and figs. 6 and 7 of PL II. of 

 Gervais' Paleont. Franc, may be referred to. 



An abnormal condition of the crochet in the last molar of 



1 The specimen here referred to is 

 described in detail in Dr. Falconer's Note- 

 book as ' E. hemitcechics of Grays Thur- 

 rock,' under date Oct. 18.">8. Even then 

 he noted important differences in the 

 crochet, &c. from the Minchin Hole 

 Molars ; and in his letters to M. Lartet 

 and Col. Wood in 1862 (see pages 309 



and 310), he includes the Grays Thurrock 

 Rhinoceros under E. leptorhirms (E. 'me- 

 garhinus). From some of his later notes, 

 however, it would appear that he identi- 

 fied E. hcmittxchus as also occurring in the 

 lower brick-earths of Grays Thurrock. — 

 [Ed.] 



