PETERSON: A REVISION OF THE ENTELODONTIDA 105 
but their bases indicate that they were codssified so as to form one solid spine. 
The neural canal is of considerable size and its outline anteriorly is subtrian- 
gular; it diminishes rapidly backward agreeing in its diameter with all the 
other measurements of the sacrum. ‘The chief differences revealed by the sacrum 
of Dinohyus when compared with that of Archxothervwm are the relatively smaller 
antero-posterior and transverse diameters of the centrum, the actual measurements 
of length and breadth in the former being only very little greater than those of the 
latter genus, notwithstanding the smaller size of Archxotherium. The vertical diam- 
eter of the anterior face of the centrum more nearly corresponds to that of the Oli- 
gocene genus. The prezygapophyses have, as in Archxotherium, the additional 
articular surfaces for the episphenial processes of the last lumbar vertebra. 
From material acquired in 1908 I am able to give complete illustrations (see 
figs. 60 -62) and also to more fully describe parts of the sacrum, which are partially 
or wholly lost in the type specimen. 
The reduced diameter, especially the antero-posterior, of the centra in the 
sacrum observed in the type specimen of Dinohyus hollandi is repeated in other 
individuals. In No. 2126 (Carn. Mus. Cat. Vert. Foss.) there is a complete sacrum 
(see figs. 60-62) and its measurements agree quite closely with those of the type. 
Fie, 61. Anterior and Posterior Views of Sacrum of D. hollandi Peterson. § nat. size. (Carn. Mus. Cat. Vert. 
Foss., No. 2126.) 
Anteriorly the neural canal, which is triangular in outline, is of large size and 
rapidly decreases posteriorly. All the sacral foramina are of large size. The two 
anterior spinous processes are very heavy and quite solidly codssified, except at their 
extremities,” which are slightly separated and also greatly enlarged. The spine of the 
®Tn a smaller though older specimen (No. 2139) the summit of the spines is solidly codssified and much ex- 
panded laterally. 
