PETERSON: A REVISION OF THE ENTELODONTIDA ile} 
MEASUREMENTS OF THE PATELLA. 
Vertical diameter 
Tranverse ~ ‘* 
Antero-posterior iameter...........cccccecseerseeseeeeeeteeeeee es 
Tibia. —One of the more noteworthy characters of Dinohyus is seen in the 
codssification of the tibia and fibula. In the Princeton specimen from the Oligocene 
the fibula, though much reduced, is entirely free, while in Dinohyus it is firmly 
coossified. The internal condyle extends somewhat more over the shaft than in 
Archeotheriwm, which results in a relatively greater expansion. 
The two condyles are separated by a prominent spine which 
rises more abruptly than in the older forms. The cnemial keel 
is prominent and extends very nearly to the middle of the shaft 
before it disappears. On the internal face of the cnemial crest 
the shaft is quite flat, while externally there is a large fossa for 
the flexor tendon, which is bounded superiorly by the ex- 
panded head and the deep tendinal groove, laterally by the 
high enemial keel and the rounded external border; distally 
the fossa gradually becomes shallower and finally fades away on 
the shaft below the enemial keel. Posteriorly there is another 
prominent fossa for the tibialis posticus, which is bounded above 
by the overhanging borders of the popliteal notch, and laterally 
by the internal and external borders of the bone. Distally the 
fossa fades away and the surface of the shaft is almost flat, 
while internally, externally, and anteriorly, there are greater 
conyexities imparting to the bone a sub-oval cross-section. 
More distally the shaft becomes nearly quadrate. 
The transverse expansion of the distal end is not great and 
the antero-posterior diameter is only very moderate. The troch- 
lea is unequally divided by a prominent THKGESLSS Exaee asl ORES ha = 
tero-posteriorly ; the external portion is the larger, and more of Tibia-fibula of Type of 
elevated than the internal, which causes a considerable ob- 2 ‘#landi Peterson. 4 
liquity of the trochlea. This character is more nearly like ee 
what may be observed in the Merycotdodonts (Oreodonts) than any of the recent 
Swide. The bifid termination at the anterior margin of the intercondylar ridge in 
Archxotherium is absent in Dinohyus, and instead there are two facets on the ex- 
treme antero-inferior end, which touch corresponding facets in the median portion 
of the neck of the astragalus when the tibia is flexed forward. A similar arrange- 
