Oeeurrenee. 



This peculiar Calanoid was found last summer (1903) by Dr. 

 Gkan in great abundance in an oyster-bed (Espevigpollen), situated 

 at Tysnæs, south of Bergen. It also occurred in another neigbour- 

 ing bed (Selopollen), but in not nearly sucli abundance as in the 

 first-named. Several other basins have been examined by Dr. Gkan, 

 and numerous plankton-samples kindly forwarded to me for exami- 

 nation. In none of these, however, did the present Calanoid occur. 

 Its place was tåken by other allied forms, among which Acartia 

 Clausi and A. discaadata were the commonest. 



The great importance, as regards oyster-culture, of the above- 

 mentioned oyster-beds, consists chiefly in the ease with which the 

 spat of the oyster, by suitable apparatus (the collectors) kept 

 floating in the water at some distance below the surface, may be 

 secured in any numbers, for the purpose of transference to suitable 

 feeding-grounds for further growth. This property of the beds is 

 due to their very peculiar physical conditions ; and it may be worth 

 while here to give some information upon this point. None of these 

 beds are artificial. They have originally simply formed the inner 

 part of bays, which, however, by the successive rise of the land- 

 crust, have gradually become separated from the sea, with which they 

 now only occasionally communicate through a very narrow passage. 

 The beds have therefore much the appearance of ordinary lakes, 

 and their level is also, as a rule, somewhat above that of the sea. 

 The depth of the beds varies somewhat, but seldom exceeds a few 

 fathoms ; and the bottom consists everywhere of a dark, loose mud, 

 smelling strongly of sulphuretted hydrogen. It is therefore only 

 along the rocky borders of the beds that the parent oysters are 

 found, generally firmly attached at some distance below the surface. 

 Owing to the long separation of these basins from the sea, a super- 

 ficial layer of almost fresh water is formed, and this layer seems 

 to act as an isolator, keeping the temperature of the underlying 



