scott: ENTELONYCHIA OF THE SANTA CRUZ BEDS. 
243 
The phalanges show an unusual degree of mobility and the unguals are 
converted into large, pointed and deeply cleft claws. The pes, also penta- 
dactyl, has an astragalus with almost ungrooved trochlea, elongate neck 
and small, strongly convex head. The tuber calcis is very much longer 
and more compressed than in the Toxodonta, in which the tuber is short 
and massive ; the fibular facet of the calcaneum is very large, forming a 
prominent external projection, and very oblique, presenting distally 
almost as much as dorsally. The metatarsals are extremely short, hardly 
more than one-third as long as the corresponding metacarpals ; the fifth 
(mt. V) has a great, hook-like projection from the fibular side of the 
proximal end, much as in the Santa Cruz genera of Gravigrade Edentates. 
Phalanges of the pes have not yet been obtained. A few isolated bones, 
including an ungual phalanx, show that in Asmodens, of the Deseado 
stage, the feet were of the same character as in Homalodontotherium, but 
in the very small Trimerostephanns (of the same stage) which Ameghino 
refers to the family Isotemnidse, the calcaneum and astragalus are much 
more primitive, the former having a slender, elongate tuber and a narrow, 
non-projecting fibular facet. 
Under the name of Colpodon Gaudry has given a brief description of 
the pes of Leontinia and a figure of the astragalus and calcaneum (’o6 rt , 
28, fig. 46, 30). According to this writer, Leontinia has a tridactyl pes, 
of which the calcaneum and astragalus are closely similar to those of 
Nesodon and altogether different from those of Homalodontotherium. The 
calcaneum has a short and very heavy tuber and large, but not projecting, 
fibular facet ; the astragalus has a narrow and elongate trochlea, a very 
short neck and but moderately convex head. Schlosser states (Ti, 523, 
apparently on the authority of Gaudry) that in this family the ungual 
phalanges are broad hoofs. If there is no error in attributing these foot- 
bones to Leontinia , it is perfectly evident that this genus is not referable 
to the Entelonychia at all, but to the Toxodonta, of which it forms a some- 
what aberrant, but perfectly characteristic member. So far as the structure 
of these animals is known, they resemble the Entelonychia only in having 
rooted molars, while, on the other hand, the peculiar development of 
tusks from the second upper and third lower incisors, the character of the 
skull and the hind-foot are typically Toxodont. 
