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anterior end of this Prolongation approaches, or even overlaps, externally the bind end of the meseth- 

 moid. The lateral portion of the Prolongation supports, on its dorsal surface, the me.sial edge of the 

 posterior portion of the nasal. The nasal is a relatively large, flat, subrectangular bone, traversed 

 its füll length by the supraorbital latero-sensory canal. The posterior portion of the bone forms the 

 roof of the nasal pit. The anterior portion of the bone rests in part upon the dorsal surface of the 

 anterior Prolongation of the frontal, in part upon the dorsal surface of the mesethmoid, and in part 

 closely upon the cartilage of the anterior end of the snout: and this anterior portion of the nasal pre- 

 sents the appearance of being composed of an underlying membrane component f used with an overlying 

 latero-sensory component. Be this composition of the bone as it niay, the two parts may be referred 

 to, for the present descriptive purposes, as the membrane and latero-sensory components of the bone. 

 The membrane component pro] ects slightly beyond the anterior and mesial edges of the anterior end of 

 the latero-sensory component, there resting upon the cartilage of the snout. Along the lateral edge of the 

 bone this membrane component turns downward, and so forms a lamina-shaped process which projects 

 ventrally along the lateral edge of the cartilage of the snout; and this lamina-shaped process would seem 

 to be the homologue of the process, na' described by Swinnerton on the nasal of Gasterosteus. Its 

 ventral edge extends to, oris even more or less interposed between, the anterior end of the palatine and 

 the cartilage of the end of the snout, this process of the nasal thus seeming to form part of the 

 articular surface for the anterior end of the palatine. 



In two of my specimens of Belone the membrane component of the nasal was easily detached, 

 in part or in whole, from the overlying portion of the bone; and although this may have been due 

 to a partial disintegration of the bone, due to the fact that my specimens had been long preserved in 

 alcohol and had then been boiled, it would tend to indicate that the part of the bone that so separated 

 was an independent ossification. It is a strictly and evidently ectosteal bone, and hence can not 

 represent, in any part, the bone described by Swinnerton as the preethmoid, which bone he classes 

 as ,,undoubtedly endosteal". 



Immediately anterior to the anterior end of the palatine, there is, on the lateral edge of the 

 cartilage of the snout, a small but marked eminence not shown or described by Swinnerton, but 

 which must be the preethmoid cornu of that author's nomenclature notwithstanding that it forms 

 no part of the articular surface for the palatine. The ventral edge of the laminar process of the nasal 

 reaches the base of this little process, but does not extend upon it; and between the cartilaginous 

 process and the lateral surface of the laminar process, there is a groove which receives the dorso-mesial 

 edge of the maxillary bone, the latter bone articulating in part with the cartilage here, and in part 

 with a small articular surface on the laminar process of the nasal. The maxillary thus here articulates 

 with the dorsal surface of the snout, and, furthermore, partly with an apparently membrane component 

 of the nasal bone, which component thus seems to here replace the preethmoid, and may perhaps 

 represent that bone. This membrane component of the nasal also somewhat resembles bone 2 of 

 Huxley's descriptions of Esox, and it may be the homologue of that bone and not of the preethmoid; 

 this then applying also to the process na', of the nasal of Gasterosteus. This needs more careful in- 

 vestigation than I have been able to give it, but it is evident that as the vomer has no dorsal limb, 

 the preethmoid, if not absent, must be elsewhere represented. 



The palatine of Belone is said by Swinnerton to articulate with the cranium at its anterior end 

 only, the posterior articulation being said to be wholly absent. This certainly is not true of my spe- 

 cimens. Here the lateral wing of the antorbital cartilage is not entirely occupied by the ectethraoid 



