PLEURONECTIN^ 377 



I. PLATICHTHYS FLESUS (Linnsus). 



[Synonymy under Subspecies.] 



Depth of body if to 2^ in the length, length of head 3 J to 3|. Upper profile of 

 head a little concave. Snout as long as or longer than eye, diameter of which is 5 to 

 7 in length of head ; lower eye a little in advance of upper ; interorbital ridge low, 

 rather narrow, naked (occasionally with a few tubercles) ; postocular ridge irregular, 

 more or less rugose, ending in a prominence above the operculum, which is followed 

 by a smaller and flatter projection lying just behind. Maxillary extending to below 

 anterior edge or anterior part of eye, length on ocular side 3I to 4!, on blind side 3^ 

 to 3} in that of head ; lower jaw a little projecting, 2f to 3J in head. Teeth generally 

 uniserial in both jaws, but occasionally irregularly biserial anteriorly ; dental formula 



- — ^^t — 5 Gill-rakers rather short, the tips pointed ; 7 to 13 on lower part of 



6-17 + 17-25 ^ *^ . / i f 



anterior arch. Embedded cycloid scales present all over the body between the 

 spinous scales or bony tubercles, which are variously developed, ranging from ordinary 

 ctenoid scales with spinules only on their posterior margms to complete rounded 

 tubercles ; nearly always a series of tubercles at bases of dorsal and anal fins, except 

 at the anterior and posterior ends, where the tubercles may be very small or even 

 absent altogether. About 80 pores in lateral line. Lateral line with a very low curve 

 above the pectoral fin ; a short supratemporal branch.^ Dorsal 52-67 : origin above 

 anterior edge or anterior part of eye ; highest rays i J to 2 J in length of head. Anal 

 36-46. Pectoral of ocular side with g to 12 rays (5 to 7 branched), length iJ to 25 

 in that of head. Pelvics with 6 rays. Caudal with 18 or 19 rays (i i or 12 branched), 

 a little rounded or truncate ; caudal peduncle variable, generally about as deep as 

 long. Intestine of more or less uniform diameter throughout, with 3 or 4 irregular 

 coils ; 2 very short pyloric appendages. Vertebrae 36 (11-12 -j- -4-25). Brownish, 

 greyish or olivaceous, uniform or variously blotched and mottled with darker ; some- 

 times with rounded black or orange spots ; blind side usually chalky white ; fins 

 with darker spots or short indistinct bars. 



Distribution. — Coasts of Europe, from the White Sea to the Black Sea ; entering 

 fresh water. 



Three subspecies may be recognised. 



la. PLATICHTHYS FLESUS FLESUS (Linnsus). 



^Flounder ; Fluke.] 



PUuronectes flesus, LinniEUS, 1758, Syst. Nat., ed. 10, p. 270; 1766, ed. 12, p. 457; Bloch, 17S3, 

 Naturgesch. Fische Deutsch., ii, p. 39, pi. xliv; Schneider, 1801, in Bloch, Syst. Ichth., p. 146; 

 Lacepede, 1802, Hist. Nat. Poiss., iv, p. 633 ; Shaw, 1803, Gen. Zool., iv (2). p. 301 ; Quensel, 

 1806, Vet. Akad. Handl., xxvii, p. 214 ; Donovan, 1806, N. H. Brit. Fish., iv, pi. .\civ ; Faber, 

 1828, Isis, xxi, p. 874 ; Faber, 1829, Naturg. Fische Isl., p. 144 ; Nilsson, 1S55, Skand. Faun., 

 ed. 2, Fiskar, p. 618 ; GUnther, 1862, Cat. Fish., iv, p. 450 ; Malmgren, 1864, .-Vrch. Naturgesch., 

 XXX (i), p. 294 ; Steindachner, i858, SitzBer. Akad. Wiss. VVien, Ivii (i), p. 719 ; Collett, 1875, 

 Vid.-Selsk. Forh., (1874), Till. p. 146 ; Malm. 1877, Gbteborgs Bohus. Fauna, p. 530 ; Collett, 

 1880, Vid.-Selsk. Forh., (1879), p. 82 ; Day, 1880-84, Fish. Britain, ii, p. 33, pl. cv ; Lilljeborg, 

 l8gi, Sverig. Norg. Fiskar, ii, p. 377 ; Smitt, i893,Scand. Fish., i, p. 398, pl. xxi, fig. I ; Collett, 

 1903, Vid.-Selsk. Forh., (1902), p. 99 ; Gratsianov, 1904, Zap. Russ. Georg. ObSc. St. Petersb., 

 xli (l), p, 220 ; Schnakenbeck, 1925, in Tier. Nord Ostsee, L. ii, xii (i), p. 4 ; Knipovich, 1926, 

 Trans. Inst. Sci. Explor. North, xxvii, p. 144, fig. 109 ; Schnakenbeck, 1929, in Joubin, Faun. 

 Ichth. Atlant. Nord, i, fig. ; Ehrenbaum, 1929, in DemoU and .Maier, Handb. Binnenfisch. 

 Mitteleurop., iii (3), p. iii, figs.; Ssytsch-Awerinzewa, 1930, Wiss. Meeresuntersuch., Abt. 

 Helgoland, xvii (5), p. i, figs. ; Berg, 1932, Not. Res. Inst. Espafi. Ocean., (ii). No. 58, p. 2. 



^ In one ambicolorate example this has a fairly long posterior prolongation. 



