368 PATAGONIAN EXPEDITIONS'. 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-\b] 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 Perame/es, but quite unlike Thylacynus. The styloid 

 process is not as greatly elongated as in Borhyczna. The distal articular 

 surface (PI. LI, fig. i), unlike the condition in Thylacynus and Borhycena, 

 is concave. 



The ulna (PI. LI, figs. \-\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 Thylacymis 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, PI. 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. PI. 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 (PI. LIV, figs. 9, 14) is greatly compressed 

 laterally, with a slight median cleft. The tip has been broken, but was 



