19 



to be found at a depth o£ 3 fathoras, but at 2V2 — 2 fathoms an abundauce of long 

 broad-leaved Zostera. The white disc could be seen faiutly at a depth of 

 2 fathoms. 



Kattegat. Als Church in W.S.W. gi/-, miles (•"/;). Pure sand bottom. 

 At 5^/2 fathoms a small quautity of narrowleaved Zostera. The disc could be 

 seen to a little more than 5 fathoms. 



Langeland Belt. Off Hou (V,s). Firm (stouy) bottom. At 5 fathoms 

 scattered Zostera, from A^j., fathoms and inwards pleuty of Zostera. The disc could 

 be seen at ca. 5 fathoms. 



Fæmø Sound (-/s). Soft ground. At 4 fathoms no Zostera. At 3 — 2 

 fathoms plenty of Zostera. The disc could only be seen at ca. 1 fathom owing to 

 rough sea. 



Guldborgsund. Fhnthorn Reef in N.N.E. (Vs-) Soft ground. At 31/2 

 fathoms no Zostera. From 3 fathoms pleuty bf Zostera. The white disc could 

 ouly be seen scarcely to 3 fathoms although the water seemed to be clean and 

 transparent. 



Baltic. Off Falster. Viggerløse Church in N.W. to W.V2W. 51/2 miles (Vs)- 

 Pure sand bottom at 6 fathoms. The white disc could be seen af 4 fathoms (in the 

 neiglibourhood at Tromnæs the Zostera grows down to a depth of almost 572 fathoms). 



Baltic. In the centre of Faxe Bay (Ys)- Pure sand bottom at 6 fathoms. 

 The white disc to be seen at 47., fathoms. (Off Faxe the Zostera grows down to 

 quite 4 fathoms). 

 (For the rest, see the observation material (Chap. IX) at the end of the paper.) 



We may conclude from these observations that the grass wrack grows as 

 far down in the water as all the compouents of the sunlight reach; they are a little 

 weakened in quautity but uuciianged in quality. 



As a general rule, the grass-wrack goes deepest down in the open waters, 

 where the water is most transparent, and to a less depth in .the muddy waters of 

 the fjords. The actual data are stated in the observation material at the end of 

 the paper (p. 47); but the foUowing may be taken as the general results for our 

 different Avaters: 

 In the Lim Fjord the limit is about 3 fathoms (ca. 5.5 m.), 



- — Kattegat (Aalborg Bay) nearly 6 — (ca. ILo - ), 



- — Great Belt and Langeland Belt about . . . 5V2 — (ca. 10. 4 - ), 



- — Little Belt about 47, — (ca. 8.5 - ), 



Waters betweeu Samsø and Jutland about 5 — (ca. 9.3 - ), 



Smaaland Waters (open part) about 472 — (ca. 8.5 - ), 



The Sound and north coast of Zealand about . . 472 — 5 fathoms (ca. 8.5 — 9. .5 m.), 



Baltic (Faxe Bay) about 4 fathoms (ca. 7.3 m.), 



Baltic (off Falster) about 57. — (ca. 10.4 - ). 



The smaller sounds and bays are very similar to the Lim Fjord, so that 

 the depth limit is about 3 fathoms (ca. 5.5 m.), e. g. Guldborgsund and Fæmø 

 Sound; in Bøgestrøm eveu as low as 2 fathoms. 



Thus the depth hmit varies between nearly 6 fathoms (ca. 11 m.) in the 

 most transparent water and 2 — 3 fathoms (ca. 4—5.5 m.) in the less transparent 

 though still flowing water of the fjords. The extreme limit, ca. 6 fathoms, is a 



