42 University of California Publications in Geology [ VoL - 1 3 



in its anteroposterior extension. Besides, the tibial trochlea is rela- 

 tively shallow with its internal and external crests of about equal 

 height. The fibular articulation is oblique, while in Eumetopias this 

 articulation is nearly horizontal. In Allodesmus there is no astraglo- 

 cuboid contact or it is at least very much reduced. 



A small astragalar foramen opens proximally at the posterointernal 

 angle of the tendinal notch. This foramen is complete, as it is also 

 in the existing genus Zalophus, but in those specimens of Eumetopias 

 that were examined there appears to be only one opening, a proximal 

 one. In the seal, Phoca richardii, there is no trace of an astragalar 

 foramen or of a tendinal notch. In Eumetopias, however, the trochlea 

 has become more deeply grooved and extends backward to the plantar 

 border of the proximal face while the tendinal groove has become 

 almost unrecognizable as such. This astragalar foramen, according 

 to F. Ameghino, transmits a branch of the peroneal artery. 



In contrast with other Otariidae, the fibular facet is broad, slightly 

 convex, and subvertical, with a sharp crest or condyle between it 

 and the tibial facet. There is a deep and oblanceolate-shaped tendinal 

 groove or notch behind the trochlea ; in Eumetopias oidy a groove 

 marking its closure remains. It should be noted that the ectal facet 

 is decidedly concave, more so superiorly than inferiorly, and its disto- 

 proximal length is more than twice its width. This facet is more 

 strongly concave in Eumetopias, but its distoproximal length is much 

 less than twice its width. In this specimen the groove for the inter- 

 osseous ligament which terminates at the astragalar foramen between 

 the ectal and sustentacular facets is much deeper and wider than in 

 Eumetopias. Another difference is that the sustentacular and navicu- 

 lar facets are continuous in this astragalus. In comparing the two 

 it was noticed that there is a deep groove invading the sustentacular 

 facet in Eumetopias, ending about two-thirds the distance across the 

 head ; yet in this astragalus the groove is represented by a notch alone 

 on the internal face and at the proximal margin. There is no cuboid 

 facet, so far as can be determined, in this astragalus. The pit for 

 the ligament from the inner side of the external malleolus is well 

 marked, though no trace of it could be found in Eumetopias. 



Measurements op Astragalus 



Greatest vertical diameter 64.2 mm. 



Greatest transverse diameter 57.5 mm. 



As might be expected, the cuboid (figs. 17a, lib, 17c) is short and 

 wide, differing from Eumetopias in that it is larger and represents a 



