35 



e. g. in C4ulclborgsund, Ulvstrøin and Bøgestrøm, as well as in the inuerinost parts 

 ol' the ba^'s aud iu halfcloscd iulets and firths. The bottom is of soft mud or 

 dark, mudmixed sand. The bottom layer is hare partly formed of green algæ 

 (Cladopliora nipestris, Chætomorpha limnn, Enferomorpha, Ulva lactiica etc.^, partly 

 of Cliaraceæ (Chara, Tolypella and LamprothamnusJ. Amongst these, besides the 

 Zostera, also grow the other marine flowering piants whicli will be more particularly 

 mentioued below: Rnppia, Zannichellia and Potamogeton pectinatus. The animal 

 life is rich, though not so varied as iu the tAvo abovementioned kinds of Zostera; 

 the reason is amongst others that the brackish water fauna is poorer and more 

 uniform than that of the salt water.') 



Of the various small animal forms whicli are fixed to or crawl over the 

 leaves of the Zostera, only very few live ou the substance of the leaves, the chief 

 mass live on the microscopic piants and animals which float in the water amongst 

 the leaves; they are thus in reality connected with the Zostera only because it 

 offers them favourable conditions to procure uourishment. This is of course also 

 the case with the larger animals which live amongst the Zostera; Echinoderms 

 (starfish (Asterias rubens) etc), worms, Lamellibranchs aud snails, also Cru- 

 stacea: prawns (Palæmon etc.^, crabs (Carcinus moenas), Mysidæ, Isopods 

 (Idofhca die.) and Amphipods (Gammarns, Prof o). Most of those prowl about for 

 their prey iu the rich hunting grounds of the Zostera. 



The only form of practical importance among these auimals is the prawn 

 (PalcemoH Fabricii), which is always lished for in the Zostera vegetation. 



The fish fauna which lives in these piaces may also be briefly mentioned. 

 The most important food tish is the eel (Anguilla vulgaris), which is specially 

 connected with the Zostera vegetation during the whole of its growth (from the 

 time when it euters our waters as elver uutil it leaves us), in so far as it does 

 not go up into fresh water. Most of the catch of yellow eels takes place iu the 

 Zostera vegetation by meaus of eelseiues or otherwise. 



Of but little practical importance are such fishes as the go bie s (Gobius 

 niger, minuhis aud Ruthensparri), the fifteen-spined stickleback {Spinachia 

 vulgaris), the three-spined stickleback (Gasterosteus aculeatus, the viviparous 

 bien ny (Zoarces viviparvs), needle fish (Siphonostoma typhle), aud the sea- 

 scorpions (CoUns scorpins and buhulis), all of which are statiouary fish, iu auy case 

 for a great part of their life, iu the Zostera vegetation. Other species of fish 

 come in here at certain times, e. g. the garfish (Belone acits), li er ring (Glupea 

 harengus) aud lumpsucker (Cydopterus himpus) aud others again live here when 

 youug, e. g. the cod. 



In the various Reports from the Biological Station lists are giveu of the 

 fishes which live in the differeut kinds of Zostera vegetation. These eau be sum- 

 marized as follows: 



1) The fishes of the pure Sand-Zostera vegetation are mentioned 

 in Report IX, pp. 37—40 (Northern Kattegat), 



') At the end of this paper, in the oljservation material, notes are here and there given 

 of the i'lants growintr amongst the Zostera. 



