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side, the rectus externus muscle has its origin. Ventro-anterior to the rectus externus, and also 

 wholly on the membrane, the rectus internus has its origin. The rectus inferior runs upward and 

 backward lateral to the rectus internus, and has its origin in part on the posterior portion of the 

 membrane that closes the optic fenestra and in part on the adjoining and bounding portions of the 

 interorbital process of the parasphenoid. The rectus superior runs downward posterior to the rectus 

 inferior, anterior to the rectus externus, and lateral to the rectus internus, and has its origin on the 

 dorsal surface of the parasphenoid. The pituitary vein forms a transverse commissure across the 

 dorsal surfaces on the recti interni, and, on either side, runs dorso-posteriorly to join the jugular 

 vein as that vein enters the trigemino-facialis chamber. The internal carotid artery traverses a 

 canal that lies wholly in the parasphenoid, traversing that bone from its ventral surface to issue 

 on the dorsal surface in the region of the ventral perforation of the interorbital wall. There it gives 

 off the orbito-nasal artery, and, joining its fellow of the opposite side, passes upward in the 

 middle line, between the recti interni and immediately anterior to the transverse commissure of 

 the pituitary veins, and, piercing the membranous floor of the cranial cavity, enters that cavity. 

 Immediately anterior to the communicating branch to the internal carotid, the afferent pseudobranchial 

 artery communicates with its fellow of the opposite side by a cross-commissural branch which 

 traverses the ventral perforation of the interorbital wall. 



The ventral perforation of the interorbital wall of Dactylopterus, and some indeterminate 

 but adjoining portion of the hind end of the orbit, is thus a myodome strictly comparable to that 

 of the other fishes of the group, but it is so short, antero-posteriorly, that it appears transverse 

 instead of longitudinal in position. In Scorpaena the myodome extends almost to the hind end of 

 the basioccipital. In Peristedion it has been considerably shortened, and extends, as it does in Amia, 

 only to the hind edges of the proötics. In Dactylopterus, it has been still further shortened, and, 

 as a result of this shortening, some portion of the proötic bridge has been tilted upward so that it 

 lies in a nearly vertical transverse position and forms an apparent part of the hind wall of the orbit: 

 the myodome being, so to speak, squeezed or shoved out of the brain case into the hind end of 

 the orbit. 



The PARASPHENOID is a broad flat bone the principal features of which have just above 

 been described in describing the orbit. It suturates anteriorly with the vomer and ectethmoids, 

 posteriorly with the basioccipital, and laterally, in its posterior portion, with the proötics. Dorsally 

 it is in sutural contact, by its interorbital process, with the alisphenoids. Its ascending process, 

 on either side, is a small pointed process which suturates with the ventral end of the sharp angle 

 that separates the lateral and orbital surfaces of the proötic. On the dorsal surface of the bone, 

 between these processes, there is a transverse ridge, already described, and posterior to this ridge 

 the dorsal surface of the bone is flat and smooth, without the median longitudinal ridge usually here 

 found on the bone. This seems to indicate, as will be more fully discussed below, that the transverse 

 ridge represents the longitudinal ridge usually found in other fishes, but here greatly shortened. The 

 ridge is tall and thin and inclines upward and backward, and on its posterior surface, in the median 

 line, there is a large pit-like depression. The internal carotid foramina perforate the bone, instead 

 of lying between it and the proötics. 



The BASISPHENOID is either wanting or is indistinguishably fused with the interorbital 

 process of the parasphenoid. 



