754 MR. D. M. S. WATSON ON 
The parasphenoid (text-fig. 9, Par.Sp.), as has been described 
above, rises from the front face of the basisphenoid. It is very 
short antero-posteriorly and rises nearly vertically in the skull 
about to the level of the anterior inferior process of the prootic ; 
its upper end is then split and receives the lower end of the 
ethmoid. 
The ethmoid is a remarkable bone extremely like that of 
Endothiodon. 
Its lower border is clasped by the split upper edge of the 
parasphenoid, from which it rises as a narrow vertical plate; in 
front this 1s continued to the roof of the skull, but behind it 
Text-figure 4. 
Mormosaurus seeleyi. Palatal aspect of the type-skull, x +. 
Reference-letters as before, with :—Pr.V., Prevomer; Pat., Palatine ; 
Tr., Transverse boue. 
splits into two branches which rise to the frontals and leave 
between them a small cavity for the olfactory lobes of the brain. 
The nasal nerves leave by a pair of openings between the median 
septal part of the ethmoid and the rest of that bone. The 
