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In the occurrence of Pleur. flesus (table X) we have an analogon to 

 the various dwelling-places of the plaice and Pleur. limamla at their various 

 j'es of life. We find that the 0-group, but also the 3-group, of Pleur. 



is abundant!) - represented in the Baltic Sea, while on the contrary the 

 1-group and, particularly, the 2-group are less frequent; yet they are more 

 numerous there than in the Cattegat, where they are so rare that I have 

 formerly supposed they lived in fresh water at this age (see Beretning III. 

 Dcmsk Biol. Statim) 1893, p. 19). Its frequent occurrence in columns 1 & 2. 

 table X, at the mouths of Mariagerfjord and Limfjord. as also at Gilleleje, 

 and its scarcity in the northern Cattegat, where they are common when 

 quite young, really indicate the same. Moreover Pleur. flesus is often seen 

 immigrating into brooks, rivulets, and lakes, and are known to occur here in 

 great numbers; but the question lias never been examined with the above 

 statements to help us. — It is possible after all that some of these Pleur. 

 tfesits, 1 — 2 years old, live in the zostera region, and from this reason 

 generally avoid the flat-fish-seines; but in the Cattegat where seines may 

 very well be employed, these annual series of Pleur. flesus are not found at 

 all. That they occur in so great numbers at Bornholm is perhaps because 

 they look upon the Baltic as by half a fresh-water sea. 



That Pleur. flesus is not at home at any rate in the northern parts of 

 the Baltic Sea seems evident from li. Lundbergh's statements p. 464 in 

 » Trawl Net and Beam Trawl-Fisfamg. 1885* where he says that Pleur:'flems 

 only in very exceptional years, for instance 1883, occurs in the northern 

 parts of the Bothnian Gulf, »where this fish is else not known and where 

 he do (does) not appear in every tenth year«. 



Something like this is said also of the cod and C. scorpius which both 

 of them have pelagic young ones like the flounders. 



Though thus the 0-group of Pleur flesus is known in the Baltic Sea. 

 while that of the plaice chiefly lives in the Cattegat and the Belts, it does 

 not seem that Pleur flesus is able to breed in quite fresh water or in the 

 northern part of the Baltic Sea. Investigations into this matter, particularly 

 information as to the occurrence of eggs in fresh water, would be very 

 desirable*). 



*) Note: Not till then can we judge of tin- value of G. Duncker's: »Der Elbbutt cine 

 Varietat der Flunder« ; for though we may find specimens of Pleur. flesus with 

 -vollstandig geveiften Gesehlechtsprodukten< and >ganz junge Exeniplare- in the 

 Elbe, this does not prove that young ones can come out of the eggs, or that the 

 young ones that have been found come from the fresh water. He himself lias 

 seen no young ones which had not already grown unsymmetriral — says he. 



