HOLLAND AND PETERSON: OSTEOLOGY OF THE CHALICOTHEROIDEA. 373 
Metatarsal III (Fig. 105)—The head of Mt. III is more expanded than that 
of Mt. II, which is chiefly due to a heavy process pointing in the fibular direction 
not unlike the process on the dorso-ulnar angle of the head of Me. III, and also 
to the prominent tuberosity on the plantar face. The fibular face has two articu- 
lations for Mt. IV, a large one on the process near the dorsal face, and a smaller 
one on the fibular face of the plantar process. The two facets together form a 
conspicuous antero-posterior concavity, which fits corresponding facets on Mt. IV, 
and forms a most effective interlocking articu- 
lation when the two bones are in position. 
This condition is entirely unlike that in Titano- 
thervum, in which the lateral facets on Mt. III 
and IV are rather small, and not of an interlock- 
ing nature. In the latter genus, however, the 
cuboid reaches over and articulates with a 
considerable portion of the head of Mt. III, 
and in this way interlocks these two bones of 
the pes which is not the case in Moropus, the 
latter showing conditions more nearly like 
those in the true Rhinoceroses. Thetibialface vs (No. 17064). 3. 1, fibular view; 2, 
of the head has an unevenly convex articula- Se as 
tion for Mt. II, which is situated on a large eminence and fits into a corresponding 
_ groove on the fibular face of the head of Mt. II, already described. The articula- 
tion for the ectocuneiform is plane, triangular in general outline, and of consider- 
able obliquity, due to the ascent of the large process on the fibular angle (see Fig. 
105, 2). Asin Mt. II the shaft is cylindrical and the distal trochlea also assumes 
the same general characters. 
One of the more important generic characters of Nestoritherium pentelici is 
found in the relative length of the metatarsals. In Macrotherium Mt. IV is the 
longest, 11 Moropus and Schizotherium Mt. III and IV are of subequal length, but 
in Nestoritherrum Mt. III is decidedly the longest, a character more nearly re- 
sembling the conditions in Titanotherium than in any of the Chalicotheres, in which 
this portion of their anatomy is known. Proximally the head carries only one 
facet, that for the ectocuneiform, exactly as in Moropus and Schizotherium. In 
Nestoritherium the details of the head are very nearly as they are in the American 
form; the shaft, however, is broader transversely, the dorsal face of the trochlea 
somewhat less hemispherical, and the carina less prominent. 
Beside the relatively shorter Mt. III in Macrotherium it has even a greater 
