MARINE BIOLOGICAL STATION AT PORT ERIN. 37 



next Easter vacation, we have agreed to postpone a fuller 

 report to a future occasion, and merely to record now that 

 she found : — 



Purpura lapillus feeding almost wholly on the rock- 

 barnacles (Balanus), the appendages of which were found in 

 abundance in the alimentary canal of the mollusc. 



Patella vulgata feeding on the smaller algae, as remains of 

 red, green, and brown sea- weeds (such as Polysiphonia, Ptilota, 

 Rhodochorton, and Confervce) were identified, along with the 

 silicious cases of diatoms, such as Coscinodiscus and Eucampia, 

 and some sponge spicules both silicious and calcareous. 



Littorina littorea feeding at that time on green algae. 



Trochus zizyphinus feeding on the algse Polysiphonia and 

 Ectocarpus, along with remains of diatoms, the Hydroid Obelia 

 and sponge spicules. 



OTHER RESEARCH WORK AT PORT ERIN. 



Larval Fish and Plankton Food. 



It was pointed out recently by Dr. Johan Hjort that as 

 the young fish larvae hatched in the sea in spring are dependent 

 for food, after they have used up the supply of yolk derived 

 from the egg, upon the diatoms and other minute organisms 

 of the phyto-plankton, which also make their appearance in 

 the sea in spring, it is most important that the young fish should 

 not be hatched before the diatoms have become abundant. 

 The phyto-plankton varies to some extent as to its abundance 

 and date of appearance from year to year, the maximum ranging 

 from March to May, and it is possible that in a late year, unless 

 the first larvse are correspondingly late, the fish may be hatched 

 out in quantity before their natural food is present in sufficient 

 abundance, and there may be an enormous mortality of larvae 

 which will affect the young fish population of that year, and 

 greatly reduce the numbers in the commercial fisheries for 

 some years. 



