PLEURONECTIN.E 381 



local forms, which cannot be dealt with here. Duncker defines two distinct races : 

 trachiirus, from the Baltic and probably also from a part of the northern Arctic Ocean ; 

 and leiurus, from the North Sea. He finds that the latter race includes a number 

 of local forms. The difference between the races irachurus and leiurus is mainly 

 concerned with the extent to which the spinous tubercles are developed on the head 

 and body, but that from the Baltic is said to have a higher number of caudal vertebrae, 

 smaller number of gill-rakers, fewer dorsal and anal rays, relatively higher caudal 

 peduncle and (generally) deeper body. Judging by the .specimens in the British 

 Museum collection, as a general rule the body tends to become rougher proceeding 

 northwards from the Channel to the White Sea, but examples from Cette in the 

 Mediterranean are quite as rough as some of those from the Baltic. Of two small 

 specimens from Bohuslan, one is moderately rough, with 62 dorsal and 44 anal rays, 

 and the caudal peduncle a little longer than deep ; the other is much rougher, with 

 57 dorsal and 40 anal rays, and the caudal peduncle deeper than long. The following 

 table shows the number of dorsal and anal rays and gill-rakers in specimens from 

 selected localities : 



Doi 



alrays 



Gill-rake 



Sandeberg (1878) gave the name Pleuronectes bogdanovi to the Flounder common in 

 the White Sea, and Suvorov (1925, 1929) applied names to races from the Murman Coast 

 (Pleuronectes flesus septentrionalis, P.flesiis caninensis) . In a recent paper. Berg' recog- 

 nises five subspecies of Platichthvs flesus, namely, flesus, bogdanovi, trachurus, septen- 

 trionalis and luscus, differentiated chiefly by the number of dorsal and ana! rays and 

 the number of gill-rakers. He includes italicus with luscus, and leiurus \vit\\ flesus. 



My own work, admittedly based on a comparatively small number of specimens, 

 leads me to conclude that there is only one subspecies ranging from the White Sea to 

 the western Mediterranean. Local races do undoubtedly occur and can be recognised, 

 but it seems inadvisable to apply the system of trinomial nomenclature to these at 

 present. 



This subspecies grows to a length of about 16 inches and a weight of 4 to 6 lb. 



Reversed examples, with the eyes and colour on the left side, are very common 

 [see note on p. 28]. 



lb. PLATICHTHYS FLESUS ITALICUS (Giinther). 



Pleuronectes hippoglossus (non Linnaus). N'accari, 1822, Ittiol. Adriat., p. 11. 



Pleuronectes flesus var., Nardo, 1827, Prodr. Adriat. Ichth., p. 15, No. 131. 



? Plalessa passer [non Linnaeus), Bonaparte, 1837, Icon. Faun. Ital., (19), tig. ; Bonaparte, 1846, 



Cat. metod. Pesci Europ., p. 48 ; Costa, 1847, Faun. R. Xapoli, ii, Fasc. 55-8, p. 7. 

 ? Pleuronectes passarinus, Nardo [ex Chiereghini MS.), 1847, Sin. mod. spec. Lag. Veneto, p. 121. 

 Pleuronectes italicus, Giinther, 1862, Cat. Fish., iv, p. 452 ; Faber, 1883, Fisheries Adriatic, p. 216. 

 Pleuronectes flesus var. glabra, Jordan and Goss, 1889, Rep. U.S. Com. Fish., xiv, (1886), p. 293. 

 Pleuronectes flesus (part), Cams, 1889-93, Prodr. Faun. Medit., ii, p. 590. 



Principal characters those of the species. Prominence on postocular ridge above 

 operculum usually more or less sharp and compressed. 8 gill-rakers on lower part of 

 anterior arch ; width of lower pharyngeals about 3J in length, their inner edges less 



' 1932, ■ Not. Resum. Inst. Espan. Ocean.,' (ii). No. 58. 



