UNITY OR PLURALITY OF SPECIES. 



261 



as many as 14 ; the variation being dependent, partly on the 

 greater or less development of the talon- ridges, which are 

 very inconstant, and, as I have elsewhere stated, partly on 

 the race, sex, and size of the individual. 1 I rest the more 

 stress upon the importance of the ridge-formula, since, 

 whenever the element of quantity can be shown to hold in 

 the animal organization, it becomes a powerful aid to re- 

 search and a criterion to test the accuracy of observation. 

 In the fossil E. antiquus of Europe, the dentition of which I 

 have been able to determine with precision, the formula for 

 the three intermediate molars and the last true molar, above 

 and below, is 10 : 10, 12, 16, being nearly intermediate 

 between the Indian and African Elephants. If then, as 

 asserted, the number of bands (i.e. ridges) is less in the 

 Sumatran and Ceylon form than in the Continental Indian, 

 the ridge-formula ought to show a lower series of ciphers. 

 Professor Schlegel tells us that he has had the advantage of 

 examining at least seven skeletons, including young indi- 

 viduals, besides several skulls of E. Sumatranus, furnishing 

 ample materials for determining the number of ridges in the 

 different teeth. Yet neither he, nor any of the other ad- 

 vocates of distinctness of the species, has as yet attempted to 

 show, by adduced instances, that the numbers are less ; and 

 until that is done, the general and therefore vague assertion 

 of the fact cannot be admitted as of sufficient weight. In 

 the skull of the large Ceylon Elephant above referred to (No. 

 2656. Osteol. Cat. Coll. Surg.) the last true molar above and 

 below shows 22 ridges ; a penultimate upper right molar, in 

 the collection of Mr. Prestwich, and of undoubted authen- 

 ticity as having been imported from Ceylon, still shows 15 

 ridges, although the most anterior portion is worn out, with 

 the loss of one ridge ; while the penultimate lowest of a 

 Siunatran skull figured by De Blainville 2 distinctly shows 16 

 ridges, besides a hind talon. These instances prove, so far 

 as they go, that the ridge-forrnula is the same in the Ceylon 

 and Sumatran form as hi the Indian. 



Next, as regards the width of the bands (discs of wear). 

 This is a most deceptive character if merely regarded per se, 

 since it varies very considerably, even in the same molar, at 

 different stages of detrition : 1st, because the ivory-cores of 

 the ridges being wedge-shaped, the discs of wear are neces- 

 sarily narrower at their apex than at their base ; 2nd, 

 because, as already stated (supra, p. 238), the plane of abrasion, 



1 Quart. Jour. Geol. Soc, 1857. Vol. 

 xiii. p. 315. {Antea,^. 5. — Ed.) 



2 Osteographie: Elephants. PL ix. 



fig. 6. De Blainville numbers the tooth 

 as a 6th or last, but it is manifestly a 

 5th or penultimate. 



