ENDOCRANIAL CAST FROM A REPTILE 135 
occupied by these two is marked by a slight but distinct depres- 
sion, which is outlined by definite elevations; the posterior one 
amounting to a low, sharp ridge. From this depression rise the 
processes, above and below, which may be referred to in general 
terms as the epiphysis and ae pituitary body. 
The upper process is complex and is, perhaps, composed of 
two parts. Just posterior to the edge of the prosencephalic 
portion there are two protuberances which mark the position 
of a pair of deep pits in the upper wall of the brain case. In 
cleaning the skull it was impossible to be certain that the bottom 
of these cavities had been reached, but it seemed probable that 
it had. With the aid of a dentist’s mouth-mirror and fine 
curved awls the pyrite filling was picked out until it seemed that 
the bottom had been reached, but because of the inaccessibility 
of the cavities and their small diameter it is possible that the 
cavities may have been deeper and even that they may be the 
entrances to foramina. Cope, in describing the endocranial 
casts of a phytosaur, Belodon, and of a cotylosaurian reptile, 
_Diadectes, speaks of the ‘lateral processes of the epiphysis’ and 
in describing the skull of Belodon speaks of the process as lying 
in a “large canal which enters the posterior part of the orbit.” 
To this canal he gave the name of the orbitopineal canal and in 
certain papers speaks of the orbitopineal process on the casts. 
The function of this canal he was unable to determine, but 
suggests that it carried a nerve or blood-vessel.4 In his earlier 
papers he was inclined to the belief that Diadectes was blind 
because he could find no outlet for the- optic nerve and because 
the structure of the animal suggested that it was burrowing in 
habit; as the parietal foramen is exceptionally large in this form, 
he was inclined to believe that the orbitopineal canal might 
have carried a nerve from the large, probably functional, eye 
which occupied the parietal foramen, which in part supplied 
the necessary vision. It is impossible to tell whether such a 
canal existed in Desmatosuchus, but if it was present it was 
very small, and the author of this paper is inclined to believe 
4Dr. R. L. Moodie, in conversation with the author, has suggested that these 
processes may indicate a portion of the course of the ductus endolymphaticus. 
THE JOURNAL OF COMPARATIVE NEUROLOGY, VOL. 33, NO. 2 
