390 



OBSERVATIONS ON PLANT PLANKTON. 



independently noted in this species, as well as in C. borealis and 

 C. constrictus. In addition to the diatoms, and, as a rule, far ex- 

 ceeding them in total bulk, were the species of Ceratiuni. C. Tripos, 

 C. Fusns, and C. Fiirca were all three present in nearly every haul 

 of the nets, especially the first two species. Sometimes one pre- 

 dominated, sometimes the other ; but, as a general rule, C. Trijios 

 prevailed in the Clyde sea-area, and C. Fiisus in the northern lochs, 

 but never to the exclusion of the other. 



X =dead fragments, 

 r = rare. 



IT = very rare. 

 c = common. 



cc = very common. 

 -J-=not rare. 



