MARINE BIOLOGICAL STATION AT PORT ERIN. 



37 



May 2bth. — Diatoms much less numerous. Fine net 

 had only about one-tenth, or less, of the gatherings on 

 19th (no obvious change in weather conditions). 



All the above large catches of Diatoms consisted 

 almost entirely of Chaetoceras. It was not until a week 

 later that Rhizosolenia (fig. 13) made its appearance. It 

 reached its maximum early in June, and then gradually 

 died off. By the beginning of July the Diatoms had 

 practically disappeared. 





■ : 3B&-> 



Fig. 13. Diatom Plankton, consisting 

 mainly of Rhizosolenia semispina. 



PiO; 14. Copepod Plankton, consisting 

 wholly of Calamus helgolandictu. 



I insert here a short list just received from Mr. 

 A. Scott, giving the quantity of plankton and bis 

 estimate of tlie total aumber <>l Diatoms present in each 



