198 MEMOIRS OF THE UNIVERSITY OP CALIFORNIA 



displaced posteriorly 0.28 transdiameter. The sulcus rises on the epicene near the apex and 

 passes posteriorly in a sinuous line to the antapex. Near the posterior part it sinks deeply into 

 the body in a wide depression and forms a deep notch on the ventral face of the antapex. The 

 flagella and pores were not observed by Dogiel (1906). 



The niicleus is an ellipsoidal body in the middle of the hypocone, filled with coarse, chromatin 

 strands and three large masses of chromatin. Its major and minor axes are 0.48 and 0.37 trans- 

 diameter respectively. Brownish food masses were present in the anterior part. The surface 

 is striate with longitudinal equidistant lines or ribs with slight depressions between them. On 

 each side of the ribs, serially arranged, are small, oval platelike chromatophores, cornflower blue 

 in color. 



DiMENSioxs. — Length, 107-1 15m; transdiameter, 55-58m; axes of nucleus, 28/* 

 and 20m. 



OccrREEXC'E. — Figured by Dogiel (1906) from the Mediterranean off Naples. 

 Two individuals were taken by him, one from a surface haul, the other from a 

 depth of 50 meters. It was taken frequently in the plankton off La Jolla, 

 California, in the summer of 1906 during an outbreak of red water caused by 

 Gonyaulax. 



CoiNiPAEisox. — This species has the same definite ectoplasm as that fottnd in 

 G. gracUe, but not so highly differentiated as that in G. pachijdermatum. It 

 stands alone among the Dinoflagellata in its superb cornflower-blue coloring. 

 A faint bluish tinge is sometimes seen in G. gracile, other^vise this color is 

 entirely absent in all other species thus far described. Its thickened periplast 

 places it in the subgenus Paclujdinium, but its color isolates it. Structurally 

 it is nearest G. wilczeki Pouehet (fig. Z, 8) , a smaller stouter species with more 

 deeply incised postmargin, and greater differentiation of epicone and hj^^ocone. 



Gymnodinium conicum nom. sp. nov. 

 Text figure X, 27 

 Gymnodimum viridis Lebour (19176), p. 189, fig. 4. 



Diagnosis. — This is a small species with subovoidal body, its length 1.86 

 transdiameters ; girdle premedian, displaced 0.2 transdiameter ; sulcus extending 

 from apex to antapex; greenish yellow chromatophores. Length, 60m. Ply- 

 mouth Sound, England, June. 



Description. — The body is somewhat asymmetrical, ellipsoidal posteriorly, conical anteriorly, 

 its length 1.86 transdiameters at the widest part. The transverse and dorsoventral diameters 

 are nearly equal. The hypocone greatly exceeds the epicone in size, its length being greater by 

 0.36, with a continuously wider transdiameter. The epicone has the shape of a cone of about 

 80°, with a broad, blunt apex and slightly concave sides. It has a length on the left and riglit 

 sides of about 0.16 and 0.19 respectively of the total length of the body. Tlie sides of the 

 hypocone are subparallel, in ventral view, rounding posteriorly. In lateral view the ventral 

 side is nearly straight, the dorsal side convex. Tlie antapex is broad and rounded with a deep 

 trough on the ventral face. 



The girdle is premedian in position. Its distance from the apex on the left and right sides 

 is 0.16 and 0.19 respectively of the total length of the body. Its path is that of an irregularly 



