FLATFISHES. XOKMAN. 257 



identical with 8. cristatus Gray, but has somewhat fewer 

 scales in a longitudinal series, and a greater number 

 of dorsal and anal rays. In the type of 8. cristatus (161 

 mm.) the scales of the blind side are more or less ctenoid, 

 but in 8. cacatuw they are described as cycloid. 



REVISION OF THE SUBFAMILY RHOMBOSOLEIN.E. 



Regan's diagnosis of this subfamily (i.e., p. 495), 

 the members of which appear to form a natural and 

 w r ell-marked group, must be modified somewhat to in- 

 clude certain more primitive genera which seem to belong 

 to it. Unfortunately the material at my disposal is 

 insufficient to enable me to investigate the osteological 

 characters of these genera. 



In Pelotretis, one of the most generalised forms, the 

 anterior end of the dorsal fin is situated immediately 

 behind the nasal organ of the blind side as in the Pleu- 

 ronectinae; in Azygopus the first ray lies above the 

 posterior nostril ; in the remaining genera the fin extends 

 forward on the snout above the nasal organ. 



The jaws are almost symmetrical in Pelotretis and 

 Azygopus, and rather more strongly developed on the 

 ocular side in Psammodiscus ; in the other genera the 

 mouth is markedly asymmetrical, the jaws on the blind 

 side being strongly curved. The dentition is always more 

 strongly developed on the blind side, and the jaws of the 

 ocular side are devoid of teeth in all the more specialised 

 genera. 



The form and position of the nasal organs is of some 

 interest, since this character is considered to be of some 

 importance in the classification of the Heterosomata. In 

 the Pleuronectid subfamilies Pleuronectinae and 

 Samarinae, and throughout the family Bothidae, the nasal 

 organ of the blind side has accompanied or followed the 

 eye in its migration, and is situated nearly on the edge of 

 the head; whereas, in the Soleidae and Cynoglossidae the 

 two nasal organs are symmetrical in position. In the 

 subfamily Rhombosoleinae, we find the left nasal organ 

 nearly on the edge of the head in Pelotretis, and some- 

 what nearer to the edge of the head than is that of the 

 ocular side in Azygopus and Rhomltosolea; but in the 

 remaining genera the nasal organs are almost symmet- 

 rical. All those genera with symmetrical nasal organs 

 also agree in possessing comparatively small eyes, and 



