174 



cal limb lying between the nasal chamber and tlie inter- 

 maxillary cartilage, and the horizontal limb passing 

 inwards over the top of the cartilage. In front, however, 

 the sac lies wholly on the top of the cartilage fitting over 

 it in a curve like a cap. It ends very bluntly in front. 



Ventral nasal sac {n. sac.^). — Its position in the figure 

 is somewhat diagrammatic, as it is really situated under 

 the nasal chamber and only partly under the dorsal sac. 

 It arises from the chamber ventrally from, behind, and 

 also passes forwards. It is of very irregular shape, and 

 gives off externally a small limb which soon terminates. 

 Its true extent does not appear in the figure, as it is 

 situated obliquely dorso-ventrally. It narrows very much 

 in front and ends blindly near the outer skin, and between 

 it and the intermaxillary cartilage. 



There are no true posterior nares such as Kyle 

 describes in one specimen of a CynogJossus. The nasal 

 sacs discharge their contents by the action of the jaw 

 apparatus, and apparently fill again with sea water by the 

 latter simply passing into the nasal chamber, and thence 

 into the sacs, when the animal is swimming. No intrinsic 

 muscular action is involved, nor are the nostrils valved. 



The non-fixed parasitic Copepod Bomolochtis solece, 

 Claus, is not infrequently found in the nasal chamber of 

 the Plaice.* 



3.— The Eyes. 



We have only space to consider those features in the 

 structure and relations of the eyes and their accessory 

 organs which are peculiar to Pleuronectid fishes, and are 

 in some way associated with the asymmetry of the head. 

 The eyes are situated veiy near the anterior limit of the 



* For fisfnres. see T. Scott, Eleventh Report Fish. Board Scotland, 

 pi. v., figs. 1-10. 



