45 



The picked Dogfish is common here, but it is taken with hooks only. 



Besides Caranx trachurus also other fishes not belonging to our fauna 

 get iuto the Cattegat in autumn, e. g. the bass (Labrax hqms), which was 

 caught a few times, in 1897, in weels (cmp. above: The Zostera Belt), the 

 niullet {Midlus surmuletus), which was taken 10. Oct. 1897, and Zeus f aber 

 two specimens of which were caught in plaice-seiue at Rusmandsbanke and on 

 Herthas Flak in November and December 1898. 



In October — December, 1897, \ve caught also pretty often a small ten- 

 armed cuttlefish [Loligo media), in great numbers, tliroughout the whole of the 

 northern Cattegat, as far down as the isle of Anholt, particularly on depths 

 of 15 — 20 fathoms. At other seasons tliis pretty little cephalopod is but rarely 

 taken in the Cattegat. Its occurrence in great numbers in the autumn must 

 probably, like the occurrence of the above mentioned rare fishes, be ascribed 

 to the »warm bank-water« (the Jutland Current), which at this season, as it 

 seems regularly, pours in from the southern part of the German Sea. In 189S 

 this cuttlefish has beeu taken only once (12. July 98, in the Skagebugt, on 7 

 fathoms, journal- number 97); but the Biological Station's investigations of 

 the northern Cattegat ceased already in Septeml^er, when the Station was re- 

 moved to Nyborg, and it may possibly liave occurred up here later on, as in 

 the preceding year. 



On the 1. of August 1898 a fisherman brought a large eeg-mass, pro- 

 bably of another and larger species of Loligo {Loligo Forbesii?); it had been 

 taken north of the Læsø banks on 12 fathoms of water. 



d. The Clay Deposits. 



In the northern Cattegat the clay deposits cover considerably larger areas 

 tliau the other bottom-materials, and the vertical extension of the clay is like- 

 wise proportionally great, as it is found nearly everywhere between 20 and 

 60 fathoms. The natural conditions of the ground of this large area vary, how- 

 ever, and it may be divided into two essentially different parts. While the 

 bottom in the broader western part, to a depth of 30 fathoms, is a gradually 

 sloping plain, which forms a direct continuation of the mixed deposits, the 

 much narrower eastern part is a channel, where the ground falls from 30 

 fathoms to 50 — 60 fathoms, to rise again towards the Swedish sea-territory. 



A corresponding difference is seen in the development of the fauna on 

 the western and the eastern part, from which reason we must divide the fauna 



