Sinclair: marsupialia of the santa cruz beds. 385 
similar to that in Prothylacynus (PL XLIX, fig. 4). The internal malleolus 
is prominent. 
The fibula (PI. LVIII, fig. 9) is intermediate in shape between that of 
Prothylacynus and that of Thylacynus . Proximally, it is flatter than in the 
former genus, having the facets for the tibia and lateral sesamoid relatively 
longer. The shaft is curved sigmoidally, supporting a strong interosseous 
ridge. Distally the shaft becomes roughly circular in section. In shape, 
the articular surfaces for the astragalus and calcaneum are much the same 
as in Prothylacynus. 
In general, the pes (PI. LIV, fig. 3) resembles that of Dasyurus macu- 
latus. The trochlear surface of the astragulus (PI. LIV, fig. 10) is not as 
flat as in Amphiproviverra and Prothylacynus and is somewhat narrower 
proportionately than in the latter genus. The tibial portion is not pro- 
duced distally on the dorsal surface of the neck, as in Prothylacynus. 
The articular surfaces on the plantar aspect are substantially the same as 
in the last-mentioned genus (cf. PI. LIV, fig. 2 a). The calcaneum differs 
from that of Aniphiproviverra in lacking the deep groove for the accom- 
modation of the calcaneo-cuboidal ligament. The relative position of the 
tarsals is the same as in Prothylacynus. The cuboid lacks the notch in 
its dorsal border between the articular surfaces of the fourth and fifth meta- 
tarsals, which is so noticeable a feature in both Prothylacymis and Aniphi- 
proviverra. The shifting of the external cuneiform toward the outer side 
of the foot has progressed to about the same extent as in Prothylacynus. 
The hallux is not preserved, but from the small cup-shaped character of its 
articular surface on the entocuneiform, it is probable that it was propor- 
tionately no larger than in Dasyurus maculatus or D. viverrinus , having 
lost the opposable condition retained by Aniphiproviverra. The meta- 
tarsals interlock proximally and spread apart distally. Their distal ends 
have been destroyed in the right pes represented in the figure, but are well 
enough preserved in the left pes to show that the fourth is the longest, an 
arboreal character (Dollo, 1899 ; Bensley, 1903) retained also'in the manus, 
where, it will be remembered, the pollex is large and opposable ( cf. PI. 
LIV, fig. 4). 
Restoration of the Skeleton (PI. LXI, fig. 1). — The lack of proportion 
between head and body, which has been so often referred to in the discus- 
sion of the Santa Cruz thylacynes, is nowhere more marked than in Clado- 
sictis. The lengths of the few missing dorsal vertebrae were determined 
