1889.] The Artiodactyla. 
.Lfptoma-yx\.^\ 
Three lower premolars BachUherium FilhoL 
III. A metatarsal cannon bone; metacarpals forming a cannon bone; molars 
brachyodont (Tragulinge). 
a. Lateral digits well developed. 
Premolars entirely simple Tra^^nilus Briss. 
aa. Lateral digits weak. 
Four inferior premolars, the posterior with branch ridges ; superior premolar 3 
with strong cingulum Amphii^agulus Pomel. 
Three inferior premolars, the posterior with branch ridges ; superior premolar 3 
with strong cingulum, elongate Prodremotherium Filhol. 
IV. Metatarsals and metacarpals unknown; molars hypsodont (Hypisod- 
A diastema behind p. m. 2 : canines below not distinct from incisors. 
Hypisodiis Cope. 
Dorcatherium, an existing genus, has four well developed 
digits, and is nearest the Oreodontida^. The only difference be- 
tween that family and the present one being the presence and 
absence of the naviculocuboid bone respectively, Dorcatherium 
must be placed on the Traguloid side of the line. Probablyex- 
tinct genera will be found which will connect this genus more 
intimately with the Oreodontidae, for the slight complication of 
the premolars of extinct genera of the latter, testify to earlier 
members with simpler ones. 
Lophiomeryx and Hypertragulus must be associated with 
Dorcatherium on account of the lack of cannon bone. Lo- 
phiomeryx has an inferier type of inferior true molar, and 
like Dorcatherium has four toes on all the feet. Hypertrag- 
ulus displays greater specialization in the absence of lateral 
digits from the posterior feet. The ulna is also coossified 
with the radius, and there is a naviculocuboid bone. The 
premolar teeth are nevertheless very simple, and are separated 
by diastemata in both jaws. It must be regarded as a mod- 
ified descendant of Dorcatherium on one side of the main 
line of descent. (Plate VI.) 
In the next group the metatarsals have united while the 
metacarpals remain separate. This is the case in Leptomeryx 
of the American Oligocene. In Tragulus the premolars are 
much simpler than those of the other genera of Section III, 
