132 PROCEEDINGS OF THE GEOLOGICAL society. [Nov. 3, 
Fig. 9. Fig. 10. Fig. 11. 
Perissodactyle characters. 
III. Prososcrp1a, resembling the preceding in having toes in un- 
even number (five, fig. 13), in having a comparatively simple 
stomach and an enormous cecum, but combining, with a long 
proboscis, so many other peculiarities of structure as to merit 
the rank of a distinet group of Ungulata. 
In the ‘ Odontography’ I have termed the even-toed Ungulates 
‘isodactyle ’ and the odd-toed Ungulates ‘ anisodactyle’: which terms 
I propose to change, at the suggestion of my esteemed and learned 
friend the Rev. Mr. Rigaud, M.A., into the more appropriate terms 
‘artiodactyle’ and ‘perissodactyle’: and this change I adopt the 
more readily since the former terms have already been applied to 
certain groups in Ornithology. 
Judging of the views of Cuvier regarding the classification of the 
Hoofed Quadrupeds by his final arrangement in the 2nd edition 
of the ‘ Régne Animal,’—an arrangement essentially the same with 
all later classifications, —I did not call to mind, in 1839, the scattered 
allusions in the ‘Ossemens Fossiles’ to the more natural classifi- 
cation to which I had then been led by original observations on the 
dental, osteological and visceral characters of the Ungulata. 
I proceeded to show that the dental characters of these three groups 
were well-marked, each distinct from the other, and each having many 
characters in common; the molars few in number, huge in size, and 
with a maximum of complexity in the Proboscidians; the molars 
with a certain symmetrical character, with lobes in regular pairs, for 
example (fig. 6),'in the even-toed Ungulates;- whilst the molars, 
especially those of the upper jaw, were less symmetrical, usually 
crossed by oblique ridges (fig. 12), in the odd-toed Ungulates. The 
fore-part of the astragalus is divided into two equal facets (fig. 5) m 
the Artiodactyles ; but mto two unequal facets (fig. 11) in the Peris- 
sodactyles. Nay, the character of odd and even extends to the de- 
velopment of those excrescences called ‘horns’ and ‘antlers.’ In 
the Artiodactyles these are always developed in one or more sym- 
metrical transverse pairs. In the Perissodactyles this is never the 
case: the Rhinoceros has either one horn, or one behind the other on 
the same median line of the head, therefore essentially a single or odd 
horn. 
Cuvier first appreciated the distinctive and natural characters of 
