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The mesial process of the proötic of Scorpaena has, as it has in Scomber, anterior and posterior 

 portions, the pituitary opening of the brain case lying between the two portions. Immediately 

 posterior to the pituitary opening, a small process of the postpituitary portion of the main process, 

 projecting mesially, suturates with a corresponding process of the opposite side. Posterior to this 

 little suturating process the mesial edge of the main process is connected by synchondrosis, by a 

 median interspace of cartilage, with its fellow of the opposite side. On its dorsal surface, this inter- 

 space of cartilage is considerably wider than on its ventral surface, a thin lamina of the ventral layers 

 of the process of the proötic projecting mesially, nearly to the middle line. Posteriorly, the interspace 

 of cartilage is continuous, along the hind edge of the proötic, with the cartilage that caps the ventral 

 edge of the bone, the hind edge of these united bands of cartilage bounding the anterior end of the 

 basioccipital and connecting that bone, by synchondrosis, with the proötic. The anterior boundary 

 of the pituitary opening is formed by a small sharp process of the prepituitary portion of the mesial 

 process of the proötic. This little process lies, as already stated, against the ventral surface of the 

 hind edge of the basisphenoid, and usually extends to the middle line of the skull, where it suturates 

 with its fellow of the opposite side, thus completely cutting off the basisphenoid from all bounding 

 participation in the pituitary opening. Antero-dorsal to this little pituitary process of the prepit- 

 uitary portion of the entire process, the process suturates with the basisphenoid and the alisphenoid, 

 as in Scomber. 



The pituitary opening of the brain case of Scorpaena is closed, in the recent state, by mem- 

 brane, this membrane being slightly concave on its dorsal surface, and slightly convex on its ventral 

 surface. A slight depression is thus formed in the floor of the cranial cavity, this depression under- 

 lying the pituitary body and being the pituitary fossa. The pituitary opening of the brain case of 

 the adult Scorpaena is, accordingly, the functional equivalent of the so-called pituitary fossa (Swinner- 

 ton), or pituitary space (Parker) of teleostean embryos: and an opening, similar to this one in 

 Scorpaena, must certainly be found, at some stage, in all fishes the adults of which possess a basi- 

 sphenoid bone. But the opening, though shown in certain figures of median sections of the teleostean 

 skull, has seldom been particularly described. In Scomber I fully described it, using the word opening 

 in place of fenestra so as to avoid, as much as possible, any Suggestion of an homology. 



On the internal surface of the proötic, near the sutural corner between this bone, the alisphenoid 

 and the basisphenoid, is the internal opening of the foramen for the nervus oculomotorius. Posterior 

 and slightly lateral to the pituitary opening the mesial process of the bone is perforated by the 

 foramen for the nervus abducens, that nerve passing from the cranial cavity directly into the myo- 

 dome. Lateral to these two foramina are the internal openings of the trigeminus, facialis, profundus 

 and palatinus foramina; the first three foramina piercing the body of the bone to enter the trigemino- 

 facialis chamber, while the palatinus foramen perforates the base of the mesial process of the bone 

 and so enters the myodome. All four of these foramina lie in what is, in some specimens, a simple 

 depression, but in others a marked recess on the internal surface of the bone. The hind wall of this 

 recess looks postero-laterally and forms part of the anterior wall of the labyrinth recess, that wall 

 being represented, both dorsal and ventral to the pocket, by a low ridge of bone; the dorsal ridge 

 being continuous dorsally with the flange of bone that separates the two recesses on the internal 

 surface of the sphenotic, and the ventral ridge vanishing along the mesial boundary of the saccular 

 groove. The roof of the recess is formed by a nearly horizontal, shelf-like web of bone which extends 

 across the angle that lies between the anterior wall of the labyrinth recess and the body of the proötic 



