138 i c. CASE 
other. The upper pair are the casts of the otic cavities and mark 
approximately the position of the VIII, and probably, also, the 
VII nerves, for these two pairs escape from the skull of the 
Crocodilia in almost the same place. ‘The otic cavities were 
injured in fossilization both by pressure and by the erystalli- 
zation of the gypsum and pyrite which filled the cavities of the 
skull. It is apparent that there was a thin wall between the 
otic cavity and the brain cavity, but this has been so injured that 
it is impossible to determine the original form of the otic cavity 
or the form and position of the semicircular canals. 
Below are the large cylindrical projections which filled large 
foramina carrying the IX, X, and XI nerves and the jugular 
vein. All of these must have escaped through a common open- 
ing, as the walls of the brain are very perfect in this place and 
no other openings are present. 
Near the posterior end of the cast are slender processes which 
mark the position of the XII nerves. Above these processes 
there are small prominences which filled pits in the inner walls 
of the exoccipital bones. ‘These pits were entirely cleared, and 
it is certain that they were not the beginnings of foramina; 
their meaning is unknown. 
The whole metencephalic portion of the cast is rather high 
and narrow. It is possible that this is due in some degree to 
crushing, but there is no indication of such crushing in the skull, 
and it is probable that it is the true form. The whole cast is 
very small relative to the size of the animal, and even assuming 
that the brain occupied the whole cavity its size would be remark- 
able, though after all it is not much smaller, relatively, than the 
brain of Sphenodon or of an alligator. 
It is difficult to make any satisfactory comparison of this 
endocranial cast with the one made by Cope from the specimen 
of Belodon buceros because of the unsatisfactory nature of his 
figures, but some points can be made out. As can be seen by 
the figures in this paper, the whole shape is different, the cast 
from Belodon does not show the sharp downward curve posterior 
to the middle region. The cast of Desmatosuchus is thinner 
for its height and does not have so long a metencephalie portion. 
