456 Bulletin American Museum of Natural History. [Vol. XX\'II, 



it is present in Clcenodon, the Oxysenidpe, Sinopa, antl the Mesonychidse. 

 It seems to be correlated with the spreading of the digits and oblique position 

 of the cuboid. 



The partial homodipiamy and correspondence between the maniis and 

 pes appears very clearly in Clamodon, as figured by Matthew (1901, pp. 

 14-15, figs. 6, 7). The entocuneiform is large and its digit (I) diver- 

 gent, as is the case with the trapezium of the manus; the mesocuneiform is 

 small, like the trapezoid, and digit II is "thrust up"; the ectocuneiform 

 corresponds to the magnum; the oblique cuboid, with its astragalo-cuboid 

 contact, to the unciform with its lunar-unciform contact. The navicular is 

 analogous with the centrale. But here the strict analogy ends, for the cal- 

 caneum performs the functions of the cuneiform plus pisiform, while the 

 astragalus corresponds to both the scaphoid and lunar. 



The primitive Creodont astragalus would appear to have been one with a 

 rather narrow trochlear facet, with low tibial and high fibular-keel, astraga- 

 lar foramen, head flattened anteroposteriorly but very convex transversely, 

 neck twisted so that the long axis of the head is directed obliquely back- 

 ward; an astragalo-cuboid contact. The fibular surface always makes a 

 sharp angle with the trochlea and never a gentle angle with it as it does in 

 primitive jNIarsupials. Strong resemblances to the Periptychid type. 



Fissipedia. The astragalus may be derived from the type seen in 

 Cloenodon: i. e., Avith low rounded trochlear keels, rather narrow trochlea, 

 an astragalar foramen (preserved in certain INIustelidse), and a small astra- 

 galocuboid contact. 



Condylarthra. The astragalus in Euprotogonia is not essentially different 

 from the Creodont type; it retains the slender neck, the astragalar foramen, 

 the convex head, and apparently a slight cuboid contact, etc. The name 

 Condylarthra was given in allusion to the characters of the head of the astra- 

 galus which distinguish the order from that of the later and more specialized 

 Ungulate orders but not from many Unguiculate orders nor from early mem- 

 bers of the Typotheria. The Condylarthra are rather exceptional in the 

 lack of an astragalo-cuboid contact and it is by no means evident that Cope 

 was correct in assimiing this condition to be primitive. 



Taligrada. In the very primitive families Periptychidte and Panto- 

 lambdid<ie the cuboid was large and had a broad contact with the astragalus. 

 It appears to the writer very misleading and unwarranted to speak of this 

 as the "displaced" condition, or to say, for example, that the "astragalus 

 is widely displaced upon the cuboid," as is frequently done. On the con- 

 trary, the very primitive characters of Anisonchus, Peripti/cJtus, Pantolambda 

 and the Creodonts raise a presumption that the astragalo-cuboidal contact 

 is primitive, at least for those orders. An astragalar foramen was present 



