368 
, PATAGONIAN EXPEDITIONS I PALAEONTOLOGY. 
the trochlea and capitellum as sharply marked as in the recent genus. 
The supinator ridge is broad, terminating proximally in a hook-shaped 
process. A large entepicondylar foramen is present. 
The radius (PI. LI, figs. i-id) may be readily distinguished from that 
of Borhycena by the great width of the distal portion of the shaft. The 
head is elliptical in outline and much broader antero-posteriorly than in 
that genus. The bicipital tubercle is much larger than in Borhycena and 
is situated on the postero-external margin of the shaft. The shaft has a 
slightly greater degree of curvature than in the last-named genus. It is 
sharply triangular in cross section distally, closely resembling in this 
respect the radius of Perameles , but quite unlike Thylacynus . The styloid 
process is not as greatly elongated as in Borhycena. The distal articular 
surface (PI. LI, fig. i b), unlike the condition in Thylacynus and Borhycena , 
is concave. 
The ulna (PI. LI, figs, i-i b) lacks the backward curvature characteristic 
of Borhycena and Thylacynus. The olecranon process is slightly shorter 
and somewhat heavier than in the latter genus, and is broadly grooved 
on the inner side. The greater sigmoid cavity is deep, as in Borhycena , 
but its proximal wall is much wider. In the lesser sigmoid cavity, the 
radial facets are more widely separated than in either Thylacynus or 
Borhycena. Beneath the sigmoid cavity, on the inner side of the shaft, is 
a deep rugose pit for insertion of the brachialis muscle. The shaft is 
straight, considerably compressed laterally and broadly grooved on the 
outer side. The styloid process is hemispherical in shape. The radial 
facet is smaller than in Thylacynus and is supported on a distinct pedicle. 
The scaphoid and a few phalanges of the fore foot are preserved. The 
proximal surface of the scaphoid is narrower in dorso-palmar section than 
is Borhycena ; the magnum facet is smaller and the lunar facet more 
deeply concave than in the latter genus. The association of the phalanges 
represented in fig. 9, PL LIV, is somewhat doubtful. That those of 
the first and second row were carried with respect to each other at a con- 
siderable angle ( cf. PL LXI, fig. 2) is plainly indicated by the restriction 
of the trochlear surface of the proximal phalanx to the distal and palmar 
surfaces, and by the extension dorsally of the proximal articular surfaces 
of the phalanges of the second row. The latter are much heavier than in 
Thylacynus. The ungual (PL LIV, figs. 9, 14) is greatly compressed 
laterally, with a slight median cleft. The tip has been broken, but was 
