FALCONER ON THE AMERICAN FOSSIL ELEPHANT. 
87 
to research, and a criterion to test the accuracy of observation. In 
the fossil JE. antiquus of Europe, the dentition of which I have been 
able to determine with precision, the formula for the three interme¬ 
diate molars, and the last true molar, above and below, is 10: 10, 12, 
16, being nearly intermediate between the Indian and African Ele¬ 
phants. 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 individuals, besides several skulls of 
JE. Sumatranus , furnishing ample materials for determining the num¬ 
ber of ridges in the different teeth. Yet neither he, nor any of the 
other advocates of distinctness of the species, has as yet attempted to 
show, by adduced instances, that the numbers are less ; and until 
that is clone, 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 penul¬ 
timate upper right molar, in the collection of Mr. Prestwich, and 
of undoubted authenticity, 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 lower, of a Suma¬ 
tran skull figured by Blainville,* distinctly shows 16 ridges, besides a 
hind talon. These instances prove, so far as they go, that the ridge- 
formula is the same in the Ceylon and Sumatran form, as in 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 necessarily narrower at their apex than 
at their base ; 2nd, because, as already stated (supra p. 66), the plane 
of abrasion, instead of being perpendicular to the axis of the wedges, 
cuts them obliquely, the obliquity increasing with the advance of 
wear, and constantly tending towards the horizontal. The conse¬ 
quence is, that the width of the discs is always exaggerated in a tooth 
worn down to the base, and that the anterior discs are wider than 
the hinder ones. The only accurate method of ascertaining the 
number of ridges, within a given space, is to measure the crown, not 
at the summit, but along the base where the enamel-plates are re¬ 
flected ; the product will then give the average width of each ridge. 
The skull of the Ceylon Elephant (No. 2656, Coll. Surg.), supplies 
excellent and readily accessible materials for testing the value of the 
alleged character, in the so-called E. Sumatranus. It contains above 
* Osteographie Elephants Pl. ix. fig. 6. De Blainville numbers the tooth as 
a 6th or last, but it is manifestly a 5th, or penultimate. 
