JOHN DORY. 173 



includes the family Zeidse (John Dory, &c), Amphistiidse (ex- 

 tinct), and Pleuronectidae (Plaice, Sole, &c). In the first two 

 families the body is symmetrical about the median plane, in 

 the third family the one side, either the right or the left, is pale 

 and the other side dark ; the two eyes are on the dark side and 

 the greater part of the mouth is on the pale side. 



In the Zeidse the mouth is very protractile. The dorsal and 

 anal fins are much elongated, the former with a distinct spinous 

 portion, the latter with from one to four spines detached from 

 the non-spinous portion of the fin. The pelvic fins have one 

 spine and from six to eight soft fin-rays. A swim-bladder is 

 present. The family is a small one, and the species most 

 important in this country is the John Dory, Zeus faber, 750, Dory, 

 a fish much valued for the table. In colour the John Dory 

 is yellowish-grey, with wavy-bands, and a large black spot 

 edged with yellow. The English name John Dory is said to 

 be a corruption of an old Gascon name " Jan Doree," signifying 

 Gilt-Cock ; another derivation is from " Janitore," after St. Peter, 

 whose finger-mark was supposed to be the cause of the dark 

 patch on each side. In Germany the fish is called " Petersrisch," 

 and at Nice " Pei San Pierre." The Dory feeds on Sprats and 

 similar fishes, and it swims with the median plane of the body 

 not quite vertical, but slightly oblique. It is essentially a 

 warm water fish ; it occurs in the Mediterranean and along 

 the Atlantic coast from Madeira to Norway ; it is common in 

 the English and Bristol Channels, where it is taken in the trawl ; 

 in the North Sea it is rare. Zeus conchifer, 751, of Madeira, 

 is a larger species than the John Dory, and differs in the number 

 and disposition of the bony plates that occur in the skin at the 

 bases of the fin-rays of the dorsal and anal fins. 



The Amphistiidce are an extinct family with the single genus 

 Amphistium, from the Upper Eocene. Amphistium is interesting 

 as being in all probability the prototype of the Pleuronectid 

 fishes, before the origin of the asymmetry characteristic of that 

 family. The dorsal and anal spines are few, and in continuous 

 series with soft fin-rays; the pelvic fins have each a spine and 

 eight soft rays. 



