BRUNIQUEL, AND ITS ORGANIC CONTENTS. 
539 
needful for the comparisons in question. The grinding-surface of the permanent denti- 
tion of Equus caballus is given in “ G. Equus, pi. ii.,” with outer and inner views of the 
teeth in situ ; but these figures show the parts reduced to one-fourth the natural size. 
Side views of the skull and teeth of Equus asinus, E. hemionus , E. quagga, E. zebra , 
E. Burchellii, are also given at the same or a greater degree of reduction ; but there are 
none of the grinding-surface. They are thus with difficulty and uncertainty, if at all, 
available in comparing the characteristics of the complex grinding-surface of the premolar 
and molar teeth in extinct and existing species. 
Of the Equine teeth figured, of the natural size, in my 4 History of British Fossil 
Mammals’ (8vo, 1846), those from the upper jaw of Equus caballus are the working- 
surface of the third grinder, p 4 {op. cit., fig. 142), and of the first grinder,' p 2 (op. cit., 
fig. 151) : that from the lower jaw is of the third grinder,^ 4 (op. cit., fig. 144). From 
the upper jaw of Equus fossilis is figured the grinding-surface of p 4* * * § (op. cit., fig. 143) ; 
and, from the lower jaw, that of^p 4 {op. cit., fig. 145f). Of the Equus plicidens, from 
the upper jaw, the working-surface of the first grinder, p 2, is given in fig. 152 ; and that 
of the second grinder, p 3, in fig. 153, p. 393, op. cit. Two upper molars of a small 
extinct species called Asinus fossilis, are given in figs. 157, 158, op. cit.% 
H. v. Meyer § gives figures, of the natural size, of some upper and lower teeth of Hip- 
parion, and adds an outline figure of an upper molar of a recent Equus (tab. xxxii. fig. 34). 
Rutimeyer, in his excellent ‘ Beitrage zur Kenntniss der fossilen Pferde,’ &c., 8vo, 
1863, has adhered to the rule of my ‘History of British Fossil Mammalia,’ and has 
given the figures of the grinding-surface of the teeth of the natural size. They include, 
of Equus caballus'. — from the upper jaw, a premolar, tab. i. fig. 5, unworn, and fig. 9, 
worn, and fig. 11, a germ of a deciduous molar; from the lower jaw, tab. iii., a worn 
deciduous molar and one unworn, a premolar, p 2, a molar, ml, and three premolars, 
p2,p 3, p 4, Taf. iv. fig. 45. Of Equus fossilis, Ow., are figured, m 1, m 2, d 2, 3, 4 of 
the upper jaw, and of the lower jaw a germ or unworn crown of d 4, the premolars 
p 2,p 3, p 4, also m 2. Of Hipparion are figured, the lower deciduous molars and the 
first molar, m 1, Taf. iii. figs. 28, 29 ; also the premolars p 2 , p 3 ,p 4, and m 1, Taf. iv. 
Hensel, in his excellent account of the Hipparion mediterraneum , has given figures 
of the grinding-surface of the upper molars, Taf. iii., of that extinct Miocene species, 
which agree in generic character with the Hip. gracile from Eppelsheim. 
In the comparison of fossil Equine molars the close general conformity of character 
of grinding-surface, which serves so easily and satisfactorily to determine the genus or 
family, leaves the closer approximation, as to species, to a comparison of the details of 
* The min or breadth of the deciduous molars of this species, as represented by Rutimeyer, confirms the dif- 
ferential character of Eq. fossilis as deduced from this tooth, of which the figure is reproduced in a subsequent 
Paper, p. 567, fig. 1. 
f This figure is reproduced, p. 570, fig. 4. $ This figure is reproduced, p. 567, fig. 2. 
§ Beitrage zur Petrifaktenkunde (I. Eossile Pferdenartige Thiere, January, 1832 ) ; in ‘ Nova Acta Phys. 
Med. Akad. Naturae Curiosorum,’ &c. tom. xvi. pars post. 4to, 1833. 
