SCOTT: ENTELONYCHIA OF THE SANTA CRUZ BEDS. 269 
Nesodon; the odontoid process is a short and heavy peg and the neural 
spine is a hatchet-like plate, similar in shape to that of the genus last 
named, but longer antero-posteriorly and lower dorso-ventrally. Of the 
other vertebrse, Ameghino says merely that the centra have flat faces 
with a small fossette in the middle (’94 a , 59). 
The scapula is not known, but a well-preserved pelvis in the La Plata 
Museum, referred to this genus, differs much from that of Nesodon , owing 
to the great expansion and eversion of the ilia, which, with the shortness 
of the ischia, produce quite a Proboscidean appearance and are points of 
resemblance to Toxodon. 
The limb-bones are mostly, so far as they are known, quite elongate 
and very heavy. They are much larger in proportion to the size of the 
skull than are those of the contemporary Toxodonta and indicate animals 
which were massive and slow-moving, but with small heads. 
The humerus, which has been described and figured by Lydekker [op. 
cit ., PI. XX, fig. 1) is very peculiar. It is a large bone, measuring in H. 
cunninghami 16^ inches in length, and very heavy; the head is low 
and the internal tuberosity is much reduced, while the external one is 
very large. The shaft is stout, rounded for most of its length, becoming 
very broad and antero-posteriorly compressed distally. “Its chief char- 
acteristic is to be found in the enormous development of the deltoid 
crest, which extends three fourths down the shaft, where it terminates in 
a bold prominence, standing some three inches above the general level 
of the surface. ... In the great development of this crest the humerus 
of Homalodontotherium is approached by that of Phascolomys and the 
conformation in question suggests fossorial powers” (Lydekker, op. cit., 
pp. 45, 46). The posterior surface of the distal broadening of the shaft 
is very flat and smooth and the anconeal fossa must be variable, for 
Lydekker describes it as small and shallow and Ameghino as “profonde” 
(’94", 59). The trochlea is broad, very low and simple, saddle-shaped 
and undivided by any indication of an intercondylar ridge, but the 
external portion for the head of the radius is quite strongly convex. 
The internal epicondyle is large and prominent and not perforated by a 
foramen, while the external one is enormously developed and, with the 
extremely large supinator ridge, adds greatly to the unusual breadth of 
the distal end. 
While this humerus differs strongly in appearance from that of Neso- 
