— 4 — 



Slightlv mesial to the ridge that forms the lateral boundary of the groove on the vertex, near 

 the middle of its length, and at the anterior edge of the parieto-extrascapular bone, another cranial 

 ridge begins. Eunning at first parallel to the lateral bounding ridge of the groove on the vertex, this 

 other ridge soon curves latero-posteriorly onto the bounding ridge. near its bind end, and so leaves 

 the groove on the vertex at its postero-lateral eorner. It then curves again into the direction of the 

 bounding ridge, here lying posterior to the groove on the vertex, and continues either parallel to and 

 slightlv mesial to the line prolonged of the bounding ridge of the groove, or as a direct posterior con- 

 tinuation of that ridge. It soon terminates in a spine, this spine rising from the dorsal surface of the 

 parieto-extrascapular slightlv postero-mesial to the central point of the body of that bone, and lying 

 directly superficial to that section of the supratemporal latero-sensory canal that is lodged in the 

 bone. This spine is the parietal spine of Jordan & Gilbert's diagram of Sebastodes, and it lies approxima- 

 tely at the hind end of the parietal part of the parieto-extrascapular bone. The ridge to which the 

 spine is related is then the parietal spinous ridge , and this ridge is not the one that forms the lateral 

 boundary of the groove on the vertex, that ridge being an independent one, without related spine. 

 Immediatelv posterior to the parietal spine, or immediately lateral to its base, another cranial 

 spinous ridge begins, and running postero-laterally to the hind edge of the parieto-extrascapular 

 there terminates in the nuchal spine; this spine thus lying at the hind edge of the extrascapular 

 part of the parieto-extrascapular. 



Emery ('85), in his figure of the skull of Scorpaena scrofa, shows but a single spine on the 

 parieto-extrascapular, the spine and bone both being called by him, the external occipital. 



In the several specimens of Scorpaena porcus that were examined in this connection, the 

 anterior end of the parietal spinous ridge, instead of beginning close to the lateral bounding ridge of 

 the groove on the vertex, begins well within the groove, sometimes even near the middle of the cor- 

 responding half of the groove. It leaves the groove at its postero-lateral eorner, as in Scorpaena 

 scrofa, but it is much taller, relatively to the lateral bounding ridge of the groove, than in that fish. 

 It thus forms the apparent lateral boundary of the posterior portion of the groove, and the groove 

 has not the evenlv subquadrangular appearance that it has in Scorpaena scrofa. 



The frontal, parietal and nuchal spines of Scorpaena form the three posterior members of a 

 row of four spines, the anterior member of which is the nasal spine, lying at the hind end of the nasal 

 bone. There is thus, in this row, a spine at or near the hind edge of each of the four dermal elements 

 that form the mesial portion of each half of the dorsal surface of the skull; the four spines forming 

 a mesial row of spines. 



The remaining spines of Jordan and Gilbert's diagram of Sebastodes are the preocular, supra- 

 ocular and postocular, all three of which are found in Scorpaena. The preocular spine of this latter 

 fish lies on the free, orbital edge of the ectethmoid, near its dorso-mesial end, and forms the hind end 

 of a ridge on the dorsal surface of the ectethmoid which runs, from in front, upward backward and 

 slightly laterally. The supraoeular and postocular spines rise from the dorsal surface of the lateral 

 edge of the frontal, both lying posterior to the middle point of the orbit, and both of them proiecting 

 postero-laterallv in the direction of the lateral edge of the frontal. 



From the base of each of these three ocular spines, a ridge runs postero-mesially, the three 

 ridges converging, approximately, toward the point where the fourth tube of the supraorbital latero- 

 sensory canal leaves that canal to run backward and mesially to unite with its fellow of the opposite 

 side and thus form the supraorbital, or frontal commissure of the latero-sensory System. The point 



