1911] Kofoid: The Genus Gonyaulax. 191 



Four are at times fairly common, Gonyaulax polyedra, G. digi- 

 iale, G. diegensis and G. poly gramma; of the remainder, G. alas- 

 kensis, G. kofoidi, G. pacifica, G. scrippsae, G. spinifera, G. tria- 

 cantha, and G. turhynei are rare, and G. fragilis, G. birostris and 

 G. sphacroidea very rare. The winter plankton of tropical 

 facies brings G. hirostris, G. pacifica, G. kofoidi, G. sphae- 

 roidea, G. polygramma and G. turhynei to the coasts of southern 

 California. G. alaskensis is a northern form drifting southward 

 in the deeper plankton. G. scrippsae and G. diegensis were found 

 in the neritic plankton, the remainder in both neritic and oceanic 

 plankton. Gonyaulax triacantha has thus far been found only 

 in neritic plankton from Alaska, and the distribution of G. spini- 

 fera (sensu stricto) is imperfectly known at present, not having 

 been distinguished from G. digitale during the progress of the 

 w^ork. 



C. GENERAL DISCUSSION OF THE GENUS 

 I. Generic Characters 



1. HISTORICAL DISCUSSION 



The genus Gonyaulax was first defined by Diesing (1866) for 

 the single species {Peridi)iium spiniferum) which Claparede and 

 Lachmann (1858-1861) had previously assigned to the genus 

 Peridinium, but in their description placing special emphasis 

 upon the helicoidal form of the transverse furrow. No mention 

 is made by them of an extension of the longitudinal furrow to 

 the apex upon the epitheca. Diesing 's generic diagnosis is like- 

 wise based upon the marked displacement of the girdle which 

 results in the helicoidal form of the transverse furrow and he has 

 embodied the idea in his generic name Gonyaidax (yow [knee] 

 avKai [furrow]). Diesing 's diagnosis which follows contains no 

 reference to the extension of the longitudinal furrow upon the 

 apex. 



Gonyaulax Diesing 



Peridinii spec. Claparede 



' ' Animalcula solitaria libera symmetrica. Corpus immutabile, ovatum, 

 ecaudatum, eiliatum, lorica, tabulata, sulco, hiante transversali in pagina 

 dorsali obliquo in pagina ventrali bis geniciilato et altero longitudinali, ab 



