200 MEMOIRS OF THE UNIVERSITY OP CALIFORNIA 



The nucleus is a large ellipsoidal body in the anterior part of the organism. It is tilled with 

 fine, moniliform cliroiuatin strands. Its major and minor axes are about 0.47 and 0.36 trans- 

 diameter respectivel.y. A sacklike, bilobed pusule opens into the anterior flagellar pore. The 

 cytoplasm is finely gi-annlar, clear and transparent. Nutrition is holozoie, as the presence of 

 two large food masses indicates. One of these is yellow ochre in color and the other bhiish grey. 

 Scattered through the body are minute, dark, highly refractive granules. The color of the 

 plasma is a diffuse, light fluorite green with minute, rose red granules congregated at the apical 

 or antapical regions or both. 



The surface of the hypocone is smooth, that of the epieone is marked by longitudinal furrows 

 outlined by green lines. These are sometimes deeply impressed, and are short, fading out at 

 the girdle and near the apex. 



T)i:\rENSioxs. — Leugtli, 63-89/s- transdiameter, 44-58m; axes of nucleus, 21m 

 and 16^^. 



Occurrence. — This was taken August 6, 1917, with a No. 25 silk net, 4 miles 

 off La Jolla, California, in a liaul from 60 meters to the surface and in a surface 

 temperature of 21 ?2 C. On August 8 it was found at approximately the same 

 place, in a haul from 80 meters to the surface and a surface temperature of 

 22?5 C. On August 15 five individuals were observed in a haul 0.75 of a mile 

 otf La Jolla from 80 meters to the surface. 



Comparisons. — This species is closely related to G. Sidcafiim and G. rid)ri- 

 caxda in its coloring and general appearance, yet differs in its relative propor- 

 tions and its surface markings. It l^elongs in the subgenus Gijnniodiniiou. 



Gymnodinium corpusculum (Perty) Saville-Kent 



Text figure BB, 14 



Peridinium corpusculum Perty (1852), p. 162, pi. 7, fig. 14. 

 Gymnodinium corpusculum, Saville-Kent (1880-82), p. 443. 



Description. — A minute form with ovoidal or ellipsoidal botly, the length 1.3 transdiameters. 

 The girdle is near the posterior end, making the epieone much larger in size than the hypocone. 

 The color is light brown or greenish yellow. Length, 13/^. Fresh water in Switzerland. 



Syxoxymy. — This was figured by Perty (1852) as Pcridiuiioii cor pn senium 

 and the name changed to Gymnodiuium corpusculum by Saville-Kent (1880-82). 

 Perty 's figures lack sufficient morphological characters to estal)lish it as a good 

 species. Its affinities seem to be with Gymnodinkim, near G. musci, but avail- 

 al)le data render it unidentifiable and it must be placed in species incertae sedis 

 until fiirtlier investigation shall rediscover it and make its status definite. 



Gymnodinium costatum sp. nov. 



Plate 3, figure 33 ; text figure Z, 10 



Diagnosis. — A large species with suliovoidal l)ody, its length 1.66 transdi- 

 ameters: girdle submedian, displaced 0.22 transdiameter; sulcus extending 

 from apex to antapex; surface ridged; color, greyish pink. Length, 150/*. 

 Pacific oif La Jolla, California, June to August. 



