1847.] OWEN ON EXTINCT ANTHRACOTHERIOID QUADRUPEDS. 129 
represented in the actual creation by the widely dissevered links, Sus, 
Dicotyles, and Hippopotamus. 
The genera Adapis, Cheropotamus, Hyracotherium, Merycopota- 
mus, Iyopotamus, Anthracotherium, Dichodon, with Xiphodon, 
Dichobune, Chalicotherium and Anoplotherium, tend not only to 
bridge over the chasms now separating the few existing forms of artio- 
dactyle or even-toed Pachyderms, but to connect them so closely with 
the Ruminants as to render it inconsistent with such knowledge to 
regard the Pecora of Linnzus as the equivalent and very circum- 
scribed order which they are represented to be in our existing Systems 
of Zoology. 
Cuvier, though retainmg the Ruminantia m both editions of his 
‘Régne Animal’ as one of the eight primary orders of Mammalia, 
and even characterizing it as “ peut-¢tre le plus naturel et le mieux 
déterminé de la classe*,” had recognized in his previous and less 
systematic writings the aberrant characters of some members of this 
supposed most natural and circumscribed order. In reference to the 
didactyle feet of the Anoplotherium, for example, he says, ‘‘ that 
they resemble in part those of Pachyderms and in part those of 
Camels.” ‘Ils ont des chameux la division en deux doigts seule- 
ment, les formes des os du tarse; ils ont des pachydermes la sépara- 
tion des os du métatarse ; et les chameaux ont de leur cété, en 
commun avec les anoplothériums et d’autres pachydermes, la peti- 
tesse et la forme symmeéetrique des derniers phalanges. Les dents 
des chameaux s’éloignent, au reste, beaucoup moins de celles des 
pachydermes que les dents des autres animaux. Non-seulement les 
chameaux ont des canines, ils ont aussi des incisives 4 la machoire 
supérieure ; elles-y sont au nombre de deuxt.”’ 
The acute and experienced authors of the ‘ Remarks on the genus 
Anoplotherium, m the Proceedings of the Geological Society for 
1843-4 (p. 240),’ have shown that it is not exclusively to the Pachy- 
derms that the Anoplotherium is allied by the division of its cannon- 
bones, since the same division obtains in the Moschus aquaticus, an 
aberrant ruminant, which, like the Camels, has canine teeth. Nor is 
this fact surprising when it is remembered that the bipartition of the 
metacarpal and metatarsal bones is common to all ruminants at an 
early period of their existence, and that the ‘cannon-bone’ is not, 
therefore, an absolute character of the order, but rather a mark of a 
certain period of life in most of its members. 
In like manner the discovery by Prof. Goodsir { of the rudimental 
upper incisors and canines, and by myself of the rudimental anterior 
premolars § in a species of ruminant in which those teeth are wanting 
in the adult state, shows, as I argued in defence of my views of the 
value of the Ruminant group, when called into question by some of the 
eminent foreign zoologists at the Meeting of the British Association 
at Oxford (June 1847), that the absence of incisors and canines in 
the upper jaw is also a character not absolute in the order Ruminantia, 
but a modification or sign of a certain progress to maturity. 
* Regne Animal, ed. 1829, t. i. p. 254. + Ossemens Fossiles, iii. p. 148. 
} Report of British Association, 1838. § Odontography, p. 530. 
