Body much compressed bilaterally and extended dorso-ventrally : one side, on ■wliicli 

 the fish rests during life, opaque white, flatter than the other, which is more convex 

 and exhibits colour and markings : both ej^es on the coloured side of the head. 

 Pectoral and pelivc fins small, the former sometimes absent ; a single elongated dorsal 

 fin which extends forwards as far as or beyond the level of the dorsal eye, except in 

 one instance where it ends a little behind the eye ; a single elongated anal fin 

 extending fi-om the base of the tail to the anus, which is a short distance behind the 

 opercular apertures. 



The fishes thus characterised form a single family — the Pleuronectidce ( = side- 

 swimmers, from Greek TrXevpd, the side ; vyjx^^^ I swim). The large number of kinds 

 or species which can be distinguished among them are divided into a number of groups 

 according to the degree of difierence between them, any two species of the same group 

 being much more closely similar to one another than to the members of any other 

 group. These groups are the genera. Thus the diflerence between a plaice and a 

 sole is much greater than the diflerence between a plaice and a flounder. The plaice 

 and the flounder resemble each other in the shape of the body, in the large prominent 

 eyes, and the small terminal mouth and pointed snout. Again, if we compare a turbot 

 and a brill we find that they resemble one another very closely : they both have a deep 

 straight mouth cleft, the anterior end of which is at the extreme aj)ex of the snout, and 

 both have a more or less rhomboidal shape. 



The various kinds of sole are all distinguished from other flat fishes by the gradual 

 and regular curve formed by the outline of the body, which, excepting the tail, is 

 almost a perfect oval, the semicircular form of the snout being specially characteristic. 

 'J'he dorsal fin connnences on the snout, and is not continuous with the caudal fin ; the 

 cleft of the mouth on each side is curved downwards. The mouth is asymmetrical, the 

 jaws being stronger on the lower side, and only on this side containing teeth, which 

 are small and slender. The eyes are on the right side and small, the dorsal being in 

 advance of the ventral. The scales are small and fringed with small projecting spines, 

 that is, are of tbe kind called ctenoid. Tlie lateral line is straight from the head to the 

 tail, and runs along the middle of each side, but it also sends a curved branch forwards 

 on the head which runs parallel to the base of the dorsal fin towards the snout. 



All the Pleuronectidce exliibiting the above features are called Solea, with a 

 distinguishing adjective to indicate the particular kind or species referred to. In 

 otlier words, the species which resemble one another in these particulars and differ 

 only in more minute details are classed together in a genus which bears the Latin 

 name Solea in the universal language of Zoology. 



There are other kinds of sole besides the common sole, that is to say, there are other 

 kinds of flat-fishes which resemble the sole in all the features in which the sole difters 

 from the turbot or the flounder, but difier from it in more minute details. One kind 

 is sometimes sold tofjether with the common sole without bein" distinguished, and 

 sometimes is distinguished as the sand sole. It diflers from the common sole chiefly 



