38 



shallows north and south of Læsø are also, in part, densely overgrown witli 

 zostera. This plaut never goes deeper down thau to c. 7 fathoms of water. — 



But eveu where the zostera is developed at its best, we often find the 

 growth interrupted by, smaller or larger, uaked spots of sand, or by stoue- 

 banks with a rich algæ-vegetation. 



The bottom, which as a rule consists of sand, may in a few particularly 

 protected piaces become a little mixed with mud; here we find then many of 

 the species of fish which are mentioned above (under the tjord-region). South 

 of the harbour at Frederikshavn, which place, with most wiuds, is rather shel- 

 tered, there live for instance great numbers of Gasterosteus aculeatus, 

 Spinachia vulgaris, Zoarces viviparus, and PI. fiesus, which scarcely 

 ever occur north of the harbour or at such more exposed piaces. 



The station ary fishes in the zostera-belt are: 

 The Plaice, but generally only those of one or two years; never the fry of 



the year, and verj' rarely the older groups. They are found more parti- 

 cularly on the naked spots of sand between the zcstera. 

 The Flounder. All ages, except the fry of the year. This fish, however, is not 



very common in the north of the Cattegat; as above meutionend it is 



found only at the more protected piaces. 

 The common Dab (Fleuronectes limanda). Never the fry of the year, and 



rarely those one year of age. In contradistinctiou to the hitherto mentioned 



fiat-fishes, the tender fry of this fish lives on deeper water. The dab is 



very common in the northern part of the Cattegat. 

 The species of Pipe-fish: Siphonostoma tt/phle, Syngnatus acus, Nerophis aequo- 



reus and Nerophis opMdion. 

 The Sea-scorpions (Coftus scorpius and Cottus bubalis). Strange to tell, the 



young fish of these forms are scarcely ever seen under two indies in 



length. 

 The armed Bull-head [Agonus cataphrackis). Small fish of this species, on 



the other hånd, are caught now and then ; both quite small, pelagic ones 



(7., inch), and larger ones (c. 1 inch), living on the bottom. 

 The double-spotted Goby {Gohiits Bnthensparri), which is very common, 



and whose tender fry in the summer is swarming in numberless shoals 



among the zostera, together with the tender fry of the above mentioned 



Gobius minuius. 

 The Eel {Anguilla vidgaris) lives here in great numbers, in all sizes, both as 



yellow eel and as silver eel. It prefcrs particularly the piaces where the 



bottom is somewliat mixed with mud. 



