538 
PROFESSOR OWEN’S DESCRIPTION OF THE CAVERN OF 
and inner parts of the back surface of the crown which define a small accessory 
hind lobule or ‘ talon.’ In Equus (Plates LVII.-LIX. m 3) the greater development 
of this lobule, l, adds length to the working-surface of m 3 — as the production of the 
lobe a in advance of the fold Jc, in 2, makes that fold internal, as it is in Rhinoceros 
and Palceotherium , and adds length to the fore part of that grinder, producing it into a 
more or less acute angle. 
Specific modifications. — Premising this definition and explanation of the parts of the 
grinding-surface of the upper and lower molars of the Equine dentition, there remains 
an obstacle in carrying out the comparisons of those characters in the Cave Equines 
with other extinct and existing kinds which has opposed all who have undertaken work 
analogous to the present. 
To those, indeed, who may have access to specimens of the skulls and teeth of the 
known existing species of Equidoe, and to the teeth of defined fossil kinds, the difficulty 
is not felt in regard to the acquisition of personal conviction. But without, or away from, 
such opportunities of comparison, the help to be had from published figures of the denti- 
tion of Horses, Zebras, and Asses is very scanty, and of a kind inapplicable, or difficult 
and doubtful in its application. 
Camper has given a side view, in his sketchy style, of the left side of the mandible 
of a young Zebra, with the deciduous molars in situ, and demonstrating, for the first time, 
the deciduous canine in any Equine ((Euvres de P. Camper, 1803, vol. ii. 8vo, pi. xxvi. 
fol. figs. 1, 4). In the plate the subject is reduced one-half, and the characters of the 
grinding-surface of the molars are wanting. 
Cuvier has given a side view of the teeth in situ of Equus caballus, but reduced to 
one-fourth the natural size, in his ‘Ossemens Fossiles,’ 4to ed. 1822, p. 108, Cheval, pi. i. 
fig. 1. He has also given figures of the grinding-surface of the permanent teeth of the 
left side of the upper jaw of a horse (ib. Cheval, pi. ii. fig. 2), and of the right side of 
the lower jaw of a horse (ib. fig. 4). Similar figures of the deciduous dentition of a 
foal ( Poulain ) are added (ib. figs, 1 & 3, not figs. 1 & 2 as stated in the text, p. 105) ; 
but each of these figures is reduced to two-thirds of the natural size, and the surface 
of the grinders is little (if at all) abraded. 
The text of Cuvier leaves us to infer that the figures in pi. ii. are of the Horse ( Cheval , 
= Equus caballus) ; but the species is not more precisely denominated. Laurillard, in 
the posthumous edition of the ‘ Ossemens Fossiles,’ does not give better information. 
In the description of the plates added to that edition, Planche 59, the reference is 
merely Cheval, plate ii. (Explication des Planches, p. 28). 
I draw attention to this circumstance, because the comparisons which I have been led 
to make, and to illustrate by the accompanying drawings, between the different kinds 
of Equines have led me to suspect the possibility that the skull of an E. asinus may have 
been the subject from which the artist Huet drew the figures 2 and 4 of the plate 
Cheval, pi. ii. in the second volume of the 4to edition of the ‘ Ossemens Fossiles.’ 
The richly illustrated ‘ Osteographie’ of De Blainville does not supply what is really 
