SCOTT: ENTELONYCHIA OF THE SANTA CRUZ BEDS. 267 
theria and Toxodonta, and are one of the most characteristic features in 
the skull of the present genus. They are very short, of moderate width 
and almost plane both antero-posteriorly and transversely. In shape, 
each nasal is trapezoidal, the external border being much shorter than the 
mesial, for at both ends the bone narrows rapidly to a blunt point and 
thus anterior and posterior ends are much alike in shape. Owing to the 
depth of the median excavation of the frontals, the nasals have a long 
lateral suture with these bones, for more than half their length, in fact, 
while the maxillary suture is short, the anterior ends of the nasals pro- 
jecting freely. There is no suture with the premaxillaries, from which the 
nasals are far removed, one of the most obvious differences from the skulls 
of the contemporary Typotheria and Toxodonta. 
In correlation with the reduction of the incisors, the premaxillaries are 
very small and hardly visible when the skull is seen from the side, which 
is in striking contrast to the arrangement found in the other two suborders, 
in which these bones have great lateral extension upon the face. They 
are short, narrow transversely and low, with little or no distinction of 
horizontal and ascending ramus. The palatine processes are extremely 
small and contribute almost nothing to the long palate, but the spines are 
stout and quite elongate, separating the large and conspicuous incisive 
foramina. 
The maxillaries differ considerably in their proportions from those of 
Nesodon and Adinotherium , being relatively longer, on account of the 
reduction of the premaxillae, and lower, in correlation with the more 
brachyodont character of the teeth, and there is no such dorsal narrowing 
of the face. The maxillaries are also produced somewhat farther pos- 
teriorly over the orbits than in the latter and have quite extensive oblique 
sutures with the frontals. The infraorbital foramen occupies nearly the 
same relative position as in Adinotherium , over m- and well in advance 
of the orbit. The zygomatic process of the maxilla is rather better devel- 
oped than in Nesodon and extends farther back beneath the jugal. The 
palatine processes are very large and form much the greater part of the 
hard palate, but are deeply incised in front by the premaxillae and behind 
by the palatines. As a whole, the bony palate is much less concave trans- 
versely than in the Toxodonta, in which the strongly curved teeth, hypso- 
dont or semi-hypsodont in character, produce very prominent alveolar 
borders and a profoundly concave palate. 
