138 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Nov. 3, 
to disprove that idea: I have not observed a trace of median bipar- 
tition of the cannon-bone of the Horse, or of any of the phalanges 
it supports, at any stage of their development. And the third 
trochanter, the single stomach and sacculated czecum, the structure of 
the upper molars, truly discerned by Cuvier to be modifications of 
the Rhinoceros-type and not of the Ruminant-type of grinding sur- 
face, together with the number of dorso-lumbar vertebree, all com- 
bine to establish the subordinate character of the Zquide and their 
true perissodactyle affinities. 
With regard to the systems of the German Natur-philosophical 
and the English Quinary schools, the @ priori idea of the potency of 
the number 5 has served in neither case to supply the need, or anti- 
cipate the results, of pure inductive research as regards the solution 
of the problem of the natural affinities of the hoofed quadrupeds. 
Mr. Macleay* and his followers make the Bruta of Linnzeus 
(Edentata of Cuvier) a subdivision of the Ungulata; and Mr. 
Swainson, who has attempted most towards working out the details of 
the Quinary system, gives the following succession of the circular 
affinities of the primary groups or tribes of the Ungulata. 
1. Pachydermes. 2. Anoplotheres. 3. Edentates (ncluding the 
Monotremes). 4. Ruminants; and 5. Solipedes. Thus odd-toed, 
even-toed and proboscidian hoofed genera all meet together in the 
heterogeneous tribe No. 1; and the Anoplothere is separated by the 
Ornithorhynchus and Armadillo from the Ruminants! ; 
In Prof. Oken’s ‘ Naturphilosophie’ the Cetacea are added to the 
Pachyderms and Ruminants, in order to form the great group of 
Ungulata; and it must be admitted that this addition to the naturally 
circumscribed hoofed animals is less arbitrary than that of the long- 
clawed Hdentata. Among the typical forms of the Ungulata cited 
as examples of that division of the great group, which is made equi- 
valent to the Cetacea on the one hand and the Ruminants on the 
other, Oken selects the genus 
Hippopotamus as characterized by the Skin; 
Sus by the dental system or Tongue ; 
Elephas by the proboscis or Nose ; 
Rhinoceros __ by the large (?) Ears ; 
and Equus by the Kyes. 
But quitting these ‘jeua desprit,’ in which certain previously 
known and inductively-established groups are played with, like so many 
pieces in children’s geometrical puzzles and map-games, according to 
the predeterminedrules of thequinary-circular, or the 5-senses systems, 
let us see whither and how far the thread of comparative anatomy will 
guide us in the maze of the affinities of the recent and extinct animals 
with hoofed extremities. It is evident at first glance that the known 
genera cannot be ranged in a single linear series in the order of their 
natural affinities: it will be equally evident by the digital, the 
osteological, dental and visceral characters above adduced, that the 
Horse is not the next of kin to the Camel or Ox, even among existing 
genera; but that, the Proboscidians apart, all the other Ungulate 
quadrupeds are divisible into two natural and upen the whole parallel 
* Linn. Trans. xvi. (1833) p. 28. 
