INVERTEBRATE BOTTOM FAUNA 



501 



several stations, for instance on the northern slope of the Dogger 

 Bank (38 metres) and north-west of the Great Fisher Bank 

 {']'] metres). 



The Httle tube - worm Filigrana implexa, whose slender 

 white irregular tubes are associated in trellis - work colonies, 

 was met with over a large portion of the area examined, but 

 only in the deeper parts. Another common form is Tkeieptts 

 circi7tnaius, whose sinuous, parchment-like tube, covered with 

 fragments of shells, grains of sand, etc., is attached to foreign 

 substances such as empty 

 mussel - shells, Flustra, etc. 

 The annelid Aphrodite acu- 

 leata is characteristic of the 

 North Sea, but is as a rule 

 limited to the deeper parts 

 with soft or "mixed" bot- 

 tom, though nowhere found 

 in any great quantity. I 

 have already stated that 

 Sabella pavonia is common,^ 

 and, speaking generally, we 

 may say that as far as worms 

 are concerned the central 

 portion of the North Sea 

 does not differ typically from 

 the boreal portion of the Nor- 

 wegian Sea. 



One peculiarity of the 

 deeper parts of the central 

 North Sea is that on soft 

 bottom there is an absence 

 of the foraminifera so plenti- 

 ful in the Norwegian fjords 



very minutely the contents of the fine sieves through 

 bottom-material was passed. 



It has been mentioned that in the southernmost portion of 

 the North Sea, off the coasts of Belgium, Holland, and south- 

 eastern England, there are many forms of southern origin, 

 which are absent in more northerly latitudes ; some of them, 

 however, find their way farther north than the others, though 

 all keep to shallow waters with high temperatures. ^' ' ' 



Fig. 353- 

 Cory5tescassivelanus,Wo\\l. ,5 Reduced. (After Bell.) 



this I can assert after examining 

 which the 



This is, for 



1 On deep soft bottom we found representatives of the MaldanidK, as well as Eiimenia 

 crassa, Trophom'a glauca, Lnmbrinereis, and N'ephthys, which we also find on the coasts. 



