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investigated the latter in the daytime; probably the cod iu the Limfjord feed in 

 the nighttime. However the case may be, many Buccinmn have been devoured 

 by the cod in 1909 and 1910; and I consider it probable, that we have here the 

 reason of the smaller quantity of the whelks in 1910. To judge from the results 

 of the small bottom-sampler, the numbers of Nassa on the other hånd have not 

 decreased; I have never seen them more numerons than in the spring of 1910; 

 but so far as known Nassa is not sought after by cod or by other aniraals iu 

 Thisted Bredning, so far as I kuow. Its shell is stronger than that of Buccinmn. 



It is quite possible, however, that the supposed reduction in the numbers 

 of Buccinum is also due to other causes than the attacks of tlie cod. Buccinnm 

 belongs to the molluscs whose young do not float about iu the water; they remain 

 at the bottom wheu they have crept out of the egg-capsule; but in spite of eager 

 search iu these years we have only succeeded iu finding extremely few, 

 fully developed young in the otherwise very uumerous egg-masses, 

 which Buccinmn every spring deposits ou stoues and shells in the Bredning. Nor 

 have we been able to find, with but few exceptious, the small, fully developed, 

 free-liviug young on the bottom, where however there must be many per m^, even 

 if only one comes out of the many eggcapsules. Later iu the summer, 

 however, many eggs are found dead and not developed in the capsules 

 and many seem to be attacked by fuugi or bacteria; it is probably not 

 unreasonable to suppose that epidemics may arise, where so many Buccinum live 

 so close together. In any case the small number of quite small Buccinmn in the 

 Bredning is remarkable. The whelk seems to take several j'ears before it reaches 

 its fuU size, thus to grow slowly; if there is not a sufficient augmeutatiou from 

 the side of the young, the stock will be appreciably reduced iu the course of 

 some years. 



It is said, that these whelks have spread very much in the Limfjord during 

 the last 10 — 20 3'ears; that they first appeared in the western parts of the 

 fjord, Avhere they are now less numerous, whilst the central parts of the 

 fjord are now teeming with them. If this is really the case, that they have beeu 

 uumerous in the western parts, e. g. in Kaas Bredning, we may indeed hojie, 

 that they will also to some extent disappear in the central parts; in the western 

 parts, at any rate, they are not nearly so troublesome as elsewhere, and their 

 number is obviously much fewer per m- there. It is chiefly to the west aud uorth 

 of Mors and in Livø Bredning, that they are now so numerous. 



I may also mention here one thing more regarding the biology of Buccinmn. 

 As I can scarcely believe, that the dead fishes aud ou the whole the dead animals 

 which fall to the bottom, can provide sufficient food for these whelks, I have tried 

 to find out what they live on from the Buccinmn we caught; but I have always 

 found but small quantities in their stomachs and always only some indetermiuable 

 slime; what they feed on normally iu the Limfjord, therefore, I do not 

 know; but every thing thrown out, dead fish, dead oysters etc. are attacked by 

 them at once, so long as it is fresh. They know probably how to find similar 

 food not only among dead animals; they probably also know how to attack 

 the living animals, such as small mussels etc. How the large whelks can 

 open mussels is in faet well-known; I may refer hei'e to a paper by H. S. Colton 



