PLAICE. 



397 



each side of its body with sucli a rapid motion that 

 they seem almost to vibi'ate. These combined efforts 

 enable the fish to conceal itself almost quicker than 

 the eye can follow, and nothing can be seen but its 

 eye, which is of a lovely emerald colour." The Plaice 

 is also capal)le of making speedy migrations; and it is 

 M'cll known that a Hsliing-ground may one day afford 

 an abundant catch, and the next be entirely unproduc- 

 tive. Brehm" also quotes the perhajjs exaggerated state- 

 ment of a captain who said that for a whole day he 

 had M'atched the Plaice swimming one after another 

 over a sandbank, in a slioal so dense that not a glimpse 

 of the bottom could l)e seen, though the water was 

 clear and transparent. 



The Plaice also inhabits fresh water. Kroyer 

 found it'', though the specimens were only small, in 

 Gaarby Lake, at the extreme north of Jutland; and 

 Feddersen" assigns it to the Laastrup, a stream that 

 falls into Liim Fjord. Blanchere also states'^ that it 

 freely ascends the French rivers which have a sandy 

 bottom, as the Loire, Garonne, Dordogne etc. In the 

 Dordogne it is even said to deposit its spawn. 



The Plaice feeds on all those marine animals which, 

 like itself, prefer a sandy bottom, small fishes, chiefly 

 Sand-eels (Ammodytes), and lower organisms, princip- 

 ally mussels, the shells of which it crushes with its 

 pharyngeal teeth. In most cases the anterior part of 

 the intestine is crammed wdth bits of mussel-shells. 

 Annelids, crustaceans, and Echinoderms (sea-urchins and 

 starfish) also form an important part of its diet. 



In Bohusljln the spawning-season of the Plaice 

 begins in early spring, in April according to Ekstrom, 

 or even in February according to Malji". Kroyer ob- 

 serves that even in December he has found the ovaries 

 well-developed, and during mild winters has met with 

 breeding Plaice even in January. In a female nearly 

 ^' , k"rm. in weight Buckland-'^ found the ovaries to 

 Aveigh nearly ^'j of the weight of the fish, and he 

 estimated the number of the eggs at 144,600. Hensen 

 arrived at the following results'': 



The average .size of the ripe eggs of the Plaice, 

 according to the latter writer, is I'T — I'S nun. They 

 are then transparent, colourless and without oil-globules. 

 In salt water they float, but in brackish water they 

 sink to the bottom. The newly-hatched fry, according 

 to Hensen, are about 5"26 mm. long, with pigmented 

 eyes, a large vitelline sac, and the vent close to the 

 latter. According to observations made by Mobius and 

 Heincke in an aquarium the transference of the eye in 

 the young specimens is completed in four weeks. During 

 the summer they are met ^vith in inlets and at shallow 

 spots with a sandy bottom. At the end of July, ac- 

 cording to Kroyer, the fry are about 3 in. long; and 

 Fries forwarded to the Royal Museum )-oung Plaice 

 between 70 and 83 mm. long, which had been taken 

 in BohuslUn in July, 1835. It seems doubtful, how- 

 ever, whether these latter specimens belonged to the 

 fry of that year*. As late as the end of September, 

 Sandeberg's Expedition of 1877 obtained young Plaice, 

 between 29 and 43 mm. long, oft' Waideguba to the 

 extreme west of Kola Peninsula, that had not yet ac- 

 quired the characteristic row of protuberances behind 

 the eyes. Fry of this size are distinguished by the 

 gray colour of the body, densely mottled with dark 

 brown and red spots, a colour which they still retain 

 at a length of 70 — 80 mm., when the row of pro- 

 tuberances has already appeared. The most trustworthy 

 character, to distinguish them from tlie fry of the 

 following species, consists in the number of the fin 

 rays, the somewhat deeper form of the body, and the 

 shorter peduncle of the tail. The length of the base 

 of the anal fin — more than half that of the body — 



« Thierlcben, Bd. 8, p. 192. 

 '' Tidskrift for Fiskeri, l:ste Aarg., p. 44. 

 '■ Xalurhist. Tidskr. Kbhvn, ser. 3, vol. XII, p. 70. 

 "^ Nouv. Diet. Gen. des Feches, p. 03C. 



•• As we have remarked above, some of the Bohuslan Plaice purchased in Stockholm in 1889 were evidently ready to spavvn at the 

 begiiming of JIarch. 



/ Nat. Hist. Brit. Fish., p. 180. 



«' Vierter Ber. Coram. Wiss. Unters. Deutsch. Meere (1877 — 1881), p. 300. 



'' Cf. the remarks on the growth of the preceding species. 



