2] 8 ME. F. J. COLE ON THE STRUCTURE AND MORPHOLOGY OF 



EXPLANATION OF THE PLATES. 



The figures illustrating this paper have been carefully drawn, exact size, from nature, and, it is 

 hoped, are something more than mere diagrams. The various structures and bones figured will be 

 found to occupy their natural positions — every care having been taken to ensure this. 



Plate 21. 



Fig. ] . Dissection from the left side of Gadus morrhua, showing pit organs, sensory canals, and the 

 skeletal support of the latter. Natural size. 



A. Articular. 



Ao. Angular. 



D. Dentary. 



D.F. Anterior extremity of dorsal fin. 



Fr. Frontal. 



Fr^. Triangular fossa on frontal lodging the bend of the infra-orbital canal. 



H. Hyomandibular canal. 



7.0. Infra-orbital canal. 



U. Supra-temporal portion of lateralis canal. ") , ,. 



^ [- = Lateralis canal. 



L^. Lateral portion of lateralis canal. ) 



Lg.H. Ligamentous portion of hyomandibular canal. 



La.S. Ligamentous portion of supra-orbital canal. 



L.O. First lateral line ossicle. 



N. Anterior and posterior narial openings abnormally fused together (the specimen was 



normal in this respect on the right side). 



Na. Nasal. 



0. Opercular fold. 



PcT.F. Pectoral fin. 



P.F. Post-frontal or sphenotic t Foramen for otic branch of buccal nerve. 



Plv.F. Pelvic fin. 



P.O. Pit organs (= sensory follicles). 



P. Op. Pre-operculum. 



P.T. Post-temporal or supra-scapula. 



P.T^. Upper or epiotic limb of same. 



P.T^. Lower or parotic limb of same. 



Sb.O^. First sub-orbital or lachrymal. 



Sb.O^'^. Sub-orbitals 2 to 6 (5 and 6 = first and second " post-orbitals "), 



S.O. Supra-orbital canal. 



S.O.C. Supra-orbital commissure. 



Sq. Squamosal or pterotic. 



S.T^'*. Supra- temporals ( = extra- scapulae) 1 to 4. 



The numbers denote the dermal tubules of the respective sensory canals. 



