Preliminary Remarks on the 

 Distribution and the Biology of the Zostera 

 of the Danish Seas. 



By 



C. H. Ostenfeld. 



At the request of the chief of the Danish Biological Station 

 Dr. G. G. Joh. Petersen, I made, in July— August 1901, a cruise 

 with the steamer "Sallingsund" for studying the distribution and 

 the biology of the Grass wrack (Zostera marina) in the Danish 

 Seas within the Skaw (Skagen). 



As my final report on the results of the cruise will be post- 

 poned for some time, I want to give here a short extract of my 

 studies, mostly for protecting the priority. 



1. The distribution. 



The Zostera occurs around all the Danish coasts within the 

 Skaw; it grows from a little beneath the shoreline down to a 

 depth which is different in the different parts of the Danish Seas 

 the main maximum depths are the following: — 



Kattegat c. 11 meters (nearly 6 fathoms 



Baltic Sea off the coast of Falster - 10 — (about 5Vs — 



Store Bælt - 10 — ( — 5Vs — 



Lille Bælt - 8,5 — ( — 4V» — 



Öresund - 8 — ( — 4-4Vs — 



Limfjord - 5,5 — ( — 3 — 



In the smaller fiords the depth is about the same as in the 

 Limfjord. From these figures it becomes evident that the Zostera 

 does not occur in the open sea, but only forms a girdle along 

 the coasts. Some exceptions from this rule occur, the most 

 important of which are: — 



1. In the central part of Kattegat between Læso and 



