1909.] OLFACTORY ORGAN OF TELEOSTEAN FISHES. 649 



Rhombus maximus. 



The olfactory organs lie on the ocular and blind sides of the 

 head in positions quite similar to those of Hij}j)oglossus. The 

 nostrils on the ocular side resemble those of Hipjyoglossus, except 

 that the anterior nostril is less strongly tubed and the posterior 

 nostril relatively larger. Upon the blind side the anterior nostril 

 is surrounded by a very characteristic flat circular leaf-like ex- 

 pansion (text-fig. 212, A, p. 650). A similar flap is mentioned 

 for the Brill [R. levis) by Bateson Q. c. p. 231), and, as described 

 later, occurs also in the Whiff {Arnoglossus). 



The olfactory chamber, on both sides, is oval and lodges an 

 oval rosette in which the laminae radiate in the usual way from a 

 linear raphe. 



Upon the ocular side the hinder end of the olfactory chamber 

 gives origin to a pair of accessory sacs comparable in every way 

 to those of the ocular side of Hijypoglossus. 



Upon the blind side there is only one accessory sac which has 

 the position and general relations of an ethmoidal sac, and com- 

 municates with the olfactory chamber by a wide opening above 

 the hinder part of the rosette. 



Aroioglossus megastoma. 



The nostrils are similar to those of the Tui-bot (Bateson, I. c. 

 p. 231). Upon the ocular side the olfactory chamber is oval and 

 exceedingly shallow, and is occupied by an oval rosette consisting 

 of poorly developed radiating laminee. 



An opening in the dorsal anterior ]3art of the chamber leads 

 into an ethmoidal accessory sac that lies, like that of the Turbot, 

 upon the expanded head of the maxilla, reaching as far forward 

 as the ethmo-premaxillary ligament. 



Upon the blind side the olfactory chamber is in connection 

 with one accessory sac only, which corresponds in position and 

 general relations to that upon the blind side of the Turbot. 



Solea vulgaris. 



The nostrils in this genus have been accurately described by 

 Bateson and Miss Pereyaslawzeff, and Kyle also gives a brief 

 notice of its accessory sacs. 



Upon the eyed (right) side the lower wall of the olfactory 

 organ is much contracted, so that the tubular nostrils are approxi- 

 mated, and both point almost directly backwards. The olfactory 

 chamber is, however, of fair size, and is occupied by a long oval 

 rosette with its axis nearly vertical (directed towards the centre 

 of the left eye). The position of the rosette is evidently due to 

 the backward rotation of the anterior nostril consequent upon 

 the stunted growth of the ventral wall of the chamber referred 

 to above. The laminfe of the rosette lie mainly at right angles 

 to a long central raphe, like those of the Eels ; each has a gently 

 convex free border. 



