Plate IX. 

 (Top) Ceratinm tripos with C. ftirca and Pcridiiiiuin sp., showing especially the flagellac. 

 {Bottom left) NoctihiCit scintilhtis, a phosphorcseent dinoflagcllate. 



Photographs by Leiniart Nilsson (from /,//(■ /;; tlic Sea) 



{Bottom rii^lit) Pluwocystis, photographed alive by D. P. Wilson. 



