164 
Summary. 
The spawning period of Mytilus in the Limfiord has a maxi- 
mum in May and June, but the Mytilus seems to breed throughout 
the year, as it has been found by Mytilus sp. in the Black Sea by 
Borisjak (1905). The young mussels are very phototropic, and they 
seems to prefer to get fixed at places with a slight vegetation of 
small algæ and diatoms. When fagots were set out in the Fiord 
for catching mussels, it was obvious, that the mussels only fixed 
at the upper part of the fagots, which was covered with small 
algæ and diatoms; at the part near the bottom, which was smooth 
and without vegetation at all, there never fixed a mussel. It is 
possible that this predilection for fixing at certain places with a char- 
acteristical vegetation of diatoms is the cause of the peculiar spread- 
ing in spots, which often is seem at Mytilus. 
24-1—20. 
