360 



Pari III. — Eighteenth Annual Report 



Sub-fam. Solei-pleuronectince. 



(1) and (2) As in Pleuronectince. 



(3) Ventral fins asymmetrical ; two or one. 



(4) As in Pleuronectince ? 



(5) Mouth asymmetrical, as in Pleuronectince. 



(6) Eyes on right side. 



This sub-family has already received the name Oncopterina? from 

 Jordan (32, p. 280), and it might seem as if an unnecessary reduplica- 

 tion of terms was being made. As a matter of priority, however, 

 Rhombosolea was the term given by Giinther to the genus (21, p. 557), 

 and instead of the name of the last discovered species, Oncopterus, being 

 given to the sub-family, RhombosoleinaB should rather have been 

 employed. The latter term also would have had the additional advan- 

 tage of declaring certain affinities of the group, whereas Oncopterina? is 

 an empty term. The doubt, therefore, lay between Solei-pleuronectinae 

 and Rhornbosoleime, and it is considered that the weight of the characters 

 decides in favour of the former. The asymmetrical condition of the 

 ventral fins resembles the same character in the Turbot-group certainly, 

 but, as remarked by Jordan, this is also the characteristic of the 

 Achirina? of the Sole-group. This sub-family, again, has the same 

 disposition of abdominal vertebra? — i.e., the last four to six bear hsema- 

 pophyses — as is found in certain of the Turbot-group — e.g., Rhorn- 

 boidichthys ; but this has also been shown to be a general characteristic 

 of the Soles. Hence, there is reason for considering that these 

 characters have come from the Soleidae and not the Bothinae. This is 

 further shown in the shape of the snout and mouth, which are almost 

 half-way between the types of the Sole- and Plaice-groups. In the 

 remainder of its characters, with the possible exception of the position 

 of the nasal organ of the blind side, which has not yet been determined, 

 this sub-family distinctly resembles the Plaice-group. The eyes are on 

 the right side, and the olfactory organ is the same as in the Pleuro- 

 nectinse and Hippoglossinse. 



The genera included under this sub-family are, for the present, three 

 — viz., Rhombosolea, Peltorhamphns, and Ammotretis, all from the waters 

 south of Australia, from Tasmania and New Zealand. These are so 

 distinct in their characters that — as characters are measured amongst 

 the European sjDecies — each is entitled to represent a separate genus. 

 As already mentioned, Jordan has classed with these a form from the 

 Patagonian coast of South America, namely Oncopterus. This has 

 certain remarkable resemblances to the above, but differs from them in 

 that the ventral fin is not joined to the anal, where in the above it is. 

 The interesting point to determine now is whether Oncopterus has the 

 same type of olfactory organ as the others, and a similar disposition of 

 the abdominal vertebrse. If so, then it is very probable that a number 

 of forms intermediate in their geographical distribution between the 

 above may still be found which will fall within this sub-family. 



Iruxrtce Sedis. 



Whilst it has been possible to give a certain amount of definiteness to 

 the preceding sub-families, there still remain a few forms — some of which 

 do not fall within the previous groups, and others not examined by myself 

 — which have been given a separate and sjoecial importance by the 

 American writers. As it is impossible to say exactly where the latter 

 would fall in the present scheme of classification, it is better to consider 

 them apart until further examination of their structure reveals their 

 affinities. 



