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The FRONTAL has a well developed ventral flange which comes into contact with the ali- 

 sphenoid and sphenotic, and possibly also, in some specimens, with the dorsal end of the ascending 

 process of the parasphenoid ; but the exact relations of the bones here could not be determined, for 

 their outlines were not distinct in either of my three skuUs, and I could not disarticulate the bones 

 in the one skull that I could spare for the purpose. Posterior to this ventral flange, there is a smaller 

 flange on the ventral surface of the frontal, thetwo flanges embracing the dorsal edge of the alisphenoid, 

 and the small posterior flange forming the dorsal portion of a partition between the fore and mid- 

 brain recesses of the cranial cavity. The ventral flanges of the frontals of opposite sides are relatively 

 widely separated from each other and form the lateral boundaries of the dorsal portion of the wide 

 orbital opening of the brain case. 



The frontal is bounded poeteriorly by the parieto-extrascapular and supraoccipital. Anterior 

 to the latter bone it rests directly upon the postepiphysial cartilage, this part of the bone, and also 

 the part that lies immediately anterior to it, being so thin as to be alniost transparent. The bind 

 end of the lateral edge of the bone is bounded by the pterotic, and anterior to that bone is in contact 

 with a corner of the postfrontal. 



The bone is traversed by the supraorbital canal and lodges five organs of that line, a primary 

 tube leaving the canal between each adjoining two of the five organs. There is thus one tube more in 

 this fish than in Scorpaena, this seeming to confirm the conclusion that a tube has disappeared in the 

 latter fish, as already explained. The fifth frontal organ of Cottus, the sixth one of the line, lies in the 

 small terminal tube of the canal, is well developed, and is innervated by a branch of the ophthal- 

 micus lateralis that pierces the skull from the outside and has an intracranial course, as in Scorpaena. 

 The penultimate, or sixth tube of the line anastomoses with that tube of the main infraorbital canal 

 that lies between the postfrontal and pterotic. 



The POSTFRONTAL has a postorbital position, and is, in appearance, the dorsal one of 

 two postorbital bones. This bone, however, lodges the anterior one of the two infraorbital sense 

 organs that are innervated by the ramus oticus, this definitely identifying it as a postfrontal. The 

 bind end of the dorsal edge of the bone lies on the dorsal surface of the sphenotic, the anterior and 

 larger part of this edge of the bone abutting against the lateral edge of the postorbital part of the 

 frontal. 



The PARIETO-EXTRASCAPULAR is traversed, near its bind edge, by the mesial section 

 of the supratemporal latero-sensory canal, and bears at its bind edge the parietal spine. It lodges 

 one organ of the supratemporal commissure. 



The LATERAL EXTRASCAPULAR is usually represented by two ossicles, one traversed 

 by the main infraorbital latero-sensory canal, and the other by the lateral section of the supra- 

 temporal canal, but in one of the two fishes examined, the two ossicles were fused to form a single bone. 

 The ossicle that lodges the lateral section of the supratemporal canal bridges the temporal fossa, 

 the other ossicle roofing the lateral portion of the postcommissural portion of the same fossa; the 

 commissural ossicle lying at the anterior end of the infraorbital ossicle. Each ossicle lodges a single 

 organ of the related latero-sensory line. 



The SUPRASCAPULAR has a stout, pointed epiotic process which rests upon the dorsal 

 surface of the suprascapular process of the epiotic; and a short, stout and broad opisthotic process. 

 The latter process is directed downward and forward, its flat surface lying in a somewhat transverse 



