358 



Part III. — Eighteenth Annual Report 



Fam., Soleidm. 



(1) " Preopercular margin aduate, hidden by the skin and scales 



of the head." 



(2) Olfactory laminae arranged about a rachis, which may lie 



obliquely or even transversely to the longitudinal axis of 

 the body. 



(3) Ventral fins symmetrical or asymmetrical; two, one, or 



absent altogether. 



(4) Nasal organ of blind side similarly situated to that of eyed 



side. 



(5) Mouth a symmetrical ; dentition (if present) more developed 



on blind than on eyed side ; mouth usually overhung by a 

 definite snout. 



(6) Eyes on right or left side. 



It has been thought advisable to retain the latest classification of the 

 American writers, and consider the SoleidaB as a family equivalent to 

 the preceding sub-families combined. This has the advantage of 

 dividing the Heterosomata into two main portions with an almost equal 

 number of species in each, and it has the further advantage of a suitable 

 terminology. But it has the great disadvantage of obscuring somewhat 

 the natural affinities of the various groups. For this purpose it would 

 be better if the family SoleidaB were done away with, and a classification 

 similar to that proposed earlier by the American writers (32) established. 

 In the latter, the Heterosomata were arranged in a series of sub- 

 families, two of which — SoleinaB and CynoglossinaB — represented the 

 present family. It was then possible to arrange the characters of the 

 various groups, so that the CynoglossinaB were related to the SoleinaB as 

 the SoleinaB were to the PleuronectinaB and Rhombinse, and the last two to 

 the Hippoglossime. In the more recent classification (33) the SoleidaB 

 are divided into three sub- families, AchirinaB — the American Soles, 

 SoleinaB — the European Soles, and the CynoglossinaB. Few of the 

 American Soles have been examined by myself, so that the characters 

 (2) and (4) above may not be altogether true for them, although they 

 hold good for both the SoleinaB and CynoglossinaB. 



According to the American writers, the American Soles are allied to 

 the Turbot-group (RhombinaB) in the form of their ventral fins, whilst, as 

 has been shown here, the European soles are more nearly allied to the 

 Plaice-group. On the other hand, the CynoglossinaB form an aberrant 

 group whose affinities are by no means clear. They have been derived 

 apparently from the SoleinaB or AchirinaB, but the transitional stages are 

 not yet in evidence. It is to be understood, therefore, that the affinities 

 of the various groups of Heterosomata are displayed by the sub-families, 

 whilst the families are for convenience in classification. 



The characters of the sub-families of the SoleidaB are as follows, those 

 stated by the American writers being given in brackets : — 



1. Achirinai. 



(Eyes on right side; ventral fins developed, one or both of them some- 

 times obsolete ; right ventral with extended base, confluent with 

 the anal fin.) 



Species Examined. 



Genera. 



Distribution. 



G. fascialus, . 

 S. unicolor, . 



Achirus, Lac. 



Gymnaehirus, Kaup. 

 Soleotalpa Gtr. (Apion- 

 ichthys, Kaup.). 



Tropical and temperate regions 



of America. 

 Tropical South America (?) 

 Tropical regions of Atlantic. 



