of the Fishery Board for Scotland. 



355 



the relatively slight difference in the position of the ventral fins and the 

 form of the lateral line, the description given by the American writers 

 for this genus (33, p. 2624) agrees exactly with that given for 

 Citharichthys {ibid., p. 2678), and the similar nature of the olfactory 

 organ renders it imperative to bring these two within the same sub- 

 family. 



In Tephritis, again, the ventral fins are closely approximated to one 

 another, and the laminar portions of the pubic bones are well developed 

 and reach almost to the clavicles. The ventral fin of the right or blind 

 side further shows a tendency to become reduced to four rays, and it is 

 therefore permissible for these reasons alone to regard this form as 

 transitional. 



The genera which have been included hitherto within the Turbot- 

 group are Hemirhombus, Citharichthys, and Citharus. They are 

 separated from that group, however, by the position of the ventral fins. 

 The asymmetry of these is not so great as in the Turbot-group, and the 

 pubic bones of either side never pass beyond the base of the clavicles. 

 As type of this sub-family we may choose the common Mediterranean 

 form, Citharus linguatida. This has invariably been classed with the 

 Turbots, and if the reasons advanced here for its separation from them 

 be considered valid, then the necessity of forming a distinct sub-family 

 for it and the allied genera will be admitted. 



In the " Scandinavian Fishes " it had already been noted that Citharus 

 formed an exception to the general rule in the Heterosomata bothina 

 in that it had the rays of the ventral fins close together at the base, 

 whereas in other forms they are wide apart. This external difference 

 has been shown to be associated with a more important internal differ- 

 ence in structure {vide Fig. 21), and this has been contrasted with the 

 structure of the ventral fins in Arnoylossus (Fig. 23), perhaps the nearest 

 ally to Citharus within the Turbot-group. Nor is this the only differ- 

 ence from the latter group to be observed in Citharus. Although, 

 according to Giinther (20), who had not himself examined any specimens 

 of this species, the dorsal fin extends to the snout anteriorly, it does not 

 in reality do so to the same extent as in the other genera of the Turbot- 

 group, and we find consequently in Citharus that there is a different 

 relation between the anterior extremity of the dorsal fin and the nasal 

 organ of the blind side from that in the Turbot-group. In Citharus the 

 nasal organ in question lies on the ridge of the snout, just as is the case 

 generally in the Hippoglossinse and Pleuronectinse, and as in the latter 

 group the anterior extremity of the dorsal fin inclines towards the blind 

 side on passing the upper eye, so that both nasal organs are on the 

 upper or eyed side of the dorsal fin. This position may be again 

 contrasted with that in Arnoglossus, where the nasal organ of the blind 

 side lies on the under side of the dorsal fin. 



The genera which are included within this sub-family restricted by 

 the above characters are the following : — 



[Table. 



