847.] OWEN ON EXTINCT ANTHRACOTHERIOID QUADRUPEDS. 135 
well-defined. The subsequent discovery of teeth, supposed to cha- 
racterize the Pachyderms, in the foetal state of typical ruminants ; the 
well-known occurrence of the supposed pachydermal character of the 
divided metacarpus and metatarsus, in the foetus or young of all Ru- 
minants, and its retention in the Moschus aquaticus and in a fossil 
species of Antelope ; the pachydermal modification of the foetal mem- 
branes in the Camelide, superadded to their retained upper incisors 
and canines, with the ascertained amount of visceral and osteological 
conformity of the varied group of Ruminants with the other artio- 
dactyle Ungulata ; and, above all, the number of lost links in that in- 
teresting chain which have now been restored from the ruins of a 
former world—have contributed and concurred to produce in my 
mind a different view of the nature and value of the Ruminant group, 
and to lead me to suggest a different arrangement of the recent and 
extinct Ungulate forms than are admitted in the present zoological 
systems. 
In proposing this innovation on: the established systems in my 
‘Odontography,’ I was far from expecting that it would meet with 
early or general acceptance. I was gratified indeed to find that it 
had attracted so much attention as to be made the subject of objec- 
tions, which were submitted to the Zoological Section of the British 
Association by some of the accomplished foreign zoologists (the Prince 
of Canino, Professors Nilsson and Van der Hoeven), which afforded 
me the opportunity of entermg into those details in support of my 
views which the scope of a purely anatomico-physiological treatise 
rendered inadmissible. I think it also due to myself, in here, for the 
first time, in connection with an instructive addition to the Artiodac- 
tyle group, consigning those details and arguments to paper, to take 
a brief survey of the views entertained by the most eminent zoolo- 
gists on the arrangement and sequence of the affinities of the great 
natural order Ungulata as defined by our immortal countryman Ray. 
To commence with acontemporary Zoologist and countryman who 
deservedly ranks as our highest English authority in the Mammalian 
department of Natural History,—Mr. Waterhouse. In his excellent 
‘Catalogue of the Mammalia preserved in the Museum of the Zoo- 
logical Society of London’ (8vo, 1838), he divides the hoofed species 
into the Cuvierian orders (V.) PacnypeRmMata and (VI.) Rumr- 
NANTIA: and the genera described are arranged as follows :—Sus, 
Dicotyles, Phacocherus, Tapirus, Rhinoceros, Hyrax, Equus ; then 
come the Ruminant genera beginning with Auchenia. 'The perisso- 
dactyle Pachyderms thus intervene, as in the ‘ Tableau des Vertébres’ 
in the ‘Lecons d’Anatomie Comparée,’ t.1. (1836), between the 
artiodactyle Pachyderms and the Ruminants: so that the Horse, 
Equus, may lead on to the Camelide. 
In the ‘‘ Observations on the Classification of Mammalia,”’ pub- 
lished in the ‘ Annals of Natural History’ for December 1843, Mr. 
Waterhouse calls attention to the resemblance which the genus Cen- 
tetes bears in the general structure of the skull and the greatly deve- 
loped canines to Sus, and says :—‘‘ Other Pachyderms again (as the 
Horses) approach the Rummants in a very marked degree ;” and 
the Ruminantia, which form the 7th ordinal circle in the table, p. 
VOL. IV.— PART I. L 
