PREFACE 



is but preliminary to a report on the Peridiniales col- 

 lected during the last cruise of the Carnegie . Otherwise, 

 only certain species of three other families (Peridinia- 

 ceae, Gonyaulaceae. Ceratiaceae) of the fourteen fami- 

 lies into which the order is subdivided are dealt with. 

 However, Dr. Graham's studies are of fundamental im- 

 portance to any adequate understanding of the structure 

 and relationships of the species and higher categories of 

 the Peridiniales. These studies were undertaken with 

 that particular purpose in mind. His discussion of the 

 selected species is well illustrated and gratify ingly com- 

 plete. 



Further details regarding the procedure foUow<;d in 

 making the tow-net hauls at the various oceanographic 

 stations are given in the first volume of the Biological 

 Reports of this series, "The copepods of the plankton 

 gathered during the last cruise of the Carnegie, " by 

 Charles Branch Wilson (1942). 



This manuscript was completed by Dr. Graham in 

 1938. Thus some papers printed since then are not con 

 sidered. 



J. A. Fleming 

 Director, Department of Terrestrial Magnetism 



