PLATE XXI. 



t ^ tfrf ff f ^♦^ • • • * 



m-m^mm'^imm -# r ^ # « w # • 

 '• t- # rf^## f % • • • f • 



'• ##f ^i^it^^a ill •-# 



^•li-# # i «r # l^;% s-^ i J^^»^-« 



Fig. 1. — Plankton-net Silk, Mesh of 

 No. 20, when new. x 23. 



Fig. 3. — Zoo-plankton, consisting of 

 Oithona Helgolandica ; magnified. 



Fig. 2. — The same silk after use in 

 the " Xansen '' net, for a few 

 weeks. X 23. 







■31 



m^ 



^^v 



* 





# ^* i 



1» 





■- *^> .-'/. 



Fig. 4. — Mixed Plankton, consist- 

 ing of Diatoms, Nauplii, Poly- 

 chaet larvae, etc. ; magnified. 



