84 



MEMOIRS OF THE UNIVERSITY OF CALIFORNIA 



body, and the absence of a completed permanent girdle, we liave placed it as 

 the primitive non-theeate representative of the Diniferidea and regard the 

 Adiniferidea as an offshoot of this prmiitive stock. 



Erythropsis 



Nematopsis 



Ceratium 



Dinophysidae 



Blastodiniidae 



Prorocentrum 



Exuviaella 



Gonyaulax 

 Peridinium 



Haplodinium — 



Wysoizkia 



Photochrysis 



CRYPTOMONADINA 



Fig. S. Diagram of phylogenetic derivation and relationships of the Dinotlagellata. 



The plastic or generalized nature of Protodinifer is indicated also by the 

 ease with which it progresses in either direction, though predominantly with 

 flagella]' end leading, and yet again by the fact that the transverse fiagellmn 

 may be thro^^^l about the body loosely and in either direction, though predomi- 

 nantly in the normal position of the Diniferidea. 



"With Protodinifer and Oxyrrhis recognized as primitive members of the 

 Dinofiagellata and of the Diniferidea, it is a natural conclusion to regard the 

 Gj^nnodinioidae as the basal group of the Diniferidea from which its thecate 

 representatives have sprung, while the process of evolution has continued un- 

 al)ated within its non-thecate forms with resulting high specialization in 

 Pouchetia, Cochlodinium, and Erythropsis; with colonial organization appear- 

 ing in Polykrikos; with simplification in structure in the dinoflagellate phase, 



