TECULIARITIES OF PLAICE FROM DIFFERENT FISHING GROUNDS. 329 



that plaice in the Cattegat are less spinulated when mature than those 

 of the northern part of the North Sea, and think it probable that if 

 a larger number of mature specimens from the former locality were 

 examined they would be found to exhibit as great a development of 

 spinulation. ]\Iy specimens from beyond the Dogger Lank, being taken 

 in deep water far from land, would naturally include few immature 

 specimens, and male specimens in that condition even 35 cm. in length 

 might occur nearer shore. It must be pointed out that in my specimens 

 from beyond the Dogger Bank degree 4 of spinulation only occurs in 

 specimens over 40 cm. in length, and we know from Petersen that male 

 specimens above that length occur in the Cattegat, although Duncker 

 did not obtain any. There is nothing in the results of Duncker con- 

 cerning the numerical characters to distinguish the Cattegat plaice from 

 those of the northern part of the Xorth Sea examined by me. 



Duncker examined 34 males and 48 females from the Western Baltic, 

 taken in the neighbourhood of Niendorf and Kiel. The males were 

 from 22-6 to 29-7 cm. long, the females from 22-3 to 31-2 cm. long (from 

 9 in. to little over 12 in.). We know from Holt's evidence that plaice 

 of the Western Baltic at these sizes are all, or nearly all, sexually 

 mature. The spinulation varies from degrees 2 to 5 according to my 

 notation, and it is certain that it is more strongly developed than in the 

 most spinulated of my samples, degree 1 occurring not infreciuently in 

 the females. 



The height of the body, on the average 38 to 39 per cent, according 

 to Duncker, seems to be no greater than in the Norfolk coast plaice, and 

 scarcely so great as in the specimens from beyond the Dogger Bank. 

 The length of the head is a little greater than in the northern part of 

 the North Sea. 



In the nurderical characters there is a marked reduction : the dorsal 

 rays rarely exceed 70, though instances up to 75 and one of 78 occur. 

 The ventral have a maximum of GO, but are mostly from 46 to 55. 

 In this respect the form approximates to the character of the flounder. 

 The number of tlic gill-rakers, however, is not greater than in North 

 Sea plaice, but is on the contrary rather less, the number 12 not being 

 exceeded, while in the Cattegat plaice the range of variation extends to 

 13, as in my specimens from the North Sea. 



The caudal peduncle, reaching sometimes 9 per cent., seems to be 

 rather larger than in the North Sea. 



Duncker describes four males and seven females from Greifswald, 

 a place on the coast opposite the island of lUigen, and little more 

 than 100 miles east of Kiel. On the evidence of these few specimens 

 he concludes that the Greifswald plaice ar6 on the whole different from 

 those of the neighbourhood of Kiel, and approximate in several 



