UNIVERSITY OF CALIFORNIA PUBLICATIONS 



IN 



ZOOLOGY 



Vol. 8, No. 6, pp. 295-300, pi. 19 September 14, 1911 



DINOFLAGELLATA OF THE SAN DIEGO 



REGION, V. ON SPIRAIJLAX, A NEW 



GENUS OF THE PERIDINIDA 



BY 



CHAKLES ATWOOD KOFOID 



Among the species which have been erroneously assigned to 

 the genus Gonyaulax is G. jolliffei Murray and Whitting, a com- 

 mon form in tropical seas and a regularly recurring constituent 

 of the winter plankton at San Diego. A careful analysis of its 

 plates has made its removal from the genus Gonyaulax neces- 

 sary. 



Spiraulax gen. nov. 



Characterized by the anterior plate of the ventral area not 

 meeting apical 1', or in other words, by the absence of the so- 

 called extension of the longitudinal furrow to the apex. Ventral 

 notch in the apex of apical 1'. Ventral pore absent. Form biconi- 

 cal, apices pointed, widely spreading at girdle, which is much 

 displaced but without marked overhang. Plate formula 4', 1°, 

 6", 6, 6'", 1'', i"". Precingular 6" and posterior intercalary 1" 

 very wide. The slender apical f, the so-called anterior extension 

 of the ventral furrow upon the epitheca to the apex of Gonyau- 

 lax is absent in this genus. Either the homologue of this plate 

 in Gonyaulax has dropped out entirely here, or has withdrawn 

 anteriorly from the girdle and become greatly expanded into the 



