134 MEMOIRS OF THE CARNEGIE MUSEUM 
trochlea of the astragalus displays considerable asymmetry. The external condyle 
is much higher and more produced dorsally than the internal condyle, but the 
articular surface does not extend so far distally on the anterior face as that on 
the internal condyle, which nearly meets the articulation for the navicular. The 
pit on the dorsal face, which separates the distal and proximal articulations, is large, 
comparatively shallow, and in the bottom are located two facets, which articulate 
with corresponding facets on the anterior termination of the intertrochlear ridge of 
the tibia when the latter is flexed forward. In Archwxotherium this pit is deeper 
and has no facets. The trochlear articulation of the external and internal condyles 
of Dinohyus are entirely separated by a broad sulcus, which takes up the deepest part 
of the trochlea and is directly opposite the corresponding sulcus on the intertrochlear 
ridge of the tibia when the two bones are in position. The distal trochlea is oblique 
and unequally divided into two facets, the navicular facet being larger than the 
cuboidal. The latter facet is proportionally of a less transverse diameter than that 
in the Princeton specimen, which indicates a tendency toward the narrowing up of 
the tarsus. The distal trochlea as a whole is more deeply concave on the median 
line, the ridge separating the two facets being more prominent than in the Oligocene 
genus. The sustentacular facet is relatively limited in the vertical direction and 
also somewhat narrower superiorly when compared with that in Archwotheriwm. 
There are three calcaneal facets externally ; one is situated on the extreme distal 
angle of the bone, while the other two are superior to the deep cavity which takes 
up a large area of the external face. 
The appearance of the astragalus figured by Kowalevsky (38, Pl. X XVII, fig. 
34) is not unlike that of the American genera, although the pit on the dorsal face, 
which separates the proximal and distal articulations, is apparently somewhat 
smaller in proportion than in these. 
MEASUREMENTS OF ASTRAGALUS. 
Greatest length........ 
Ch transverse diameter............ 
oe BS es (ores) oyxop-ahiae! onaxdallet leone Asean cay A Hs ledbae tion Lace 58 
A ee ie “ distal Gu ee 59 
(3 
antero-posterior diameter of astragalus. 
Calcaneum. — As in Archxotheriwm the calcaneum has a long tuber, which is 
deeply channeled externally and terminates posteriorly in an enlarged and truncated 
end, but differs from that of Archxotheriwm in having an open flat surface for the 
tendo-achillis instead of a decided groove. ‘The fibular facet is divided by an oblique 
ridge into a superior and an antero-inferior portion. The two facets are confluent, 
