PLATE XIX. 











A 







^i^,^ V 





V>J^i,:5^i:4M;^ 



.•^ 



Fig. 1. — Phyto-plankton, consisting of 

 the Diatom Rhizosolenia semispina. 



Fig. 2. — The Diatom Chcetoceras deci- 

 piens. 



Fig. 3. — Zoo-plankton, consisting of 

 the Copepod Calanus finmarckicus. 



All magnified. 



Fig. 4. — The Copepod Acartia claiisi. 

 [Fhoto-micrographs by A. Scott. 



