1894.] Geology and Paleontology. 165 
pected characters, which will be described in a full account of the spe- 
cies, with plates, which is now in preparation. Of these, the most 
striking is the structure of the fore-foot, which proves to have five well 
developed digits, although the genus is a typical artiodactyl. Hyopota- 
mus is thus the third artiodactyl genus in which the manus has been 
shown to possess five digits, the others being Oreodon from the White 
River and Protoreodon from the Uinta Eocene. Kowalowsky’s mate- 
rial belonged to many different individuals, and when put together, did 
not suggest the presence of the pollex. In the specimen before us the 
first metacarpal is proportionately much longer and heavier than in 
Oreodon ; its length is 41 mm. while that of the third metacarpal is 94 
mm. It is quite stout, especially anteroposteriorly, and laterally com- 
pressed, with well formed distal trochlea, which demonstrates the pres- 
ence of phalanges. The trapezium is large, but strange to say, has 
but slight connection with the scaphoid. The proximal surface of the 
magnum is occupied principally by the seaphoid, though to a less degree 
than in the oreodonts. The other metacarpals (II-V) are heavier than 
those which Kowalwsky has figured. 
This specimen renders it altogether probable that the earliest artio- 
dactyls were all five-toed and that the larger number of the Eocene 
members of the group will prove also to have been pentadactyl, 
though even as early as the Bridger some genera had been reduced to 
a didactyl condition —W. B. Scorr, Geological Museum, Princeton, N. 
J., Jan. 16, 1894. 
