208 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA 



The girdle is placed far anteriorly, its distance from the apex about 0.2 of the total length 

 of the body. It forms a complete circle around the body without displacement. The furrow 

 is about 0.12 transdiameter in width and deeply impressed. The sulcus begins about midway 

 between the girdle and apex and extends posteriority in a straight line to within a short distance 

 of the antapex. The Hagella and flagellar pores were not figured by Lebour (19176'). 



The nucleus is ellipsoidal and is found in the posterior half of the hypocone. It is filled 

 with loose chromatin strands. Its major and minor axes are about 0.68 and 0.37 transdiameters 

 in length respectively. Nutrition is holozoic, as indicated by the large, irregular food mass near 

 the center of the body. In Lebour 's figures the surface is marked by lines, but these are evidently 

 u.sed as contour lines, since she states that the surface is without striae. The body is clear and 

 colorless. 



Dimensions. — Length, 65/^; transdiameter, 16/*; axes of nucleus, 11m and 6m. 



OccuEKENCE. — Figured by Lebour (1917&) from water samples collected in 

 July at Plymouth Sound, England. 



Co:\iPARisoNS. — This species shows the extreme of specialization in the genus 

 in the attenuate form of the body. It is placed in the subgenus Gijnuiodiniuin 

 because it lacks striae, the scattered longitudinal lines being interpreted as 

 coutoitr lines. Should striae be present, as they may l)e, the species should be 

 transferred to the subgenus Lineadin'mm, where it would be grouped with other 

 fusiform species, such as G. cuciimis (fig. Y, 16). It is imique, whatever its 

 allocation, with no closely resembling species in Gymnodiniiun. 



Gymnodinium flavum sp. nov. 



Plate 9, figure 100; text figure X, 7 



Diagnosis. — This is a mimtte species with broadly ellipsoidal body, slightly 

 compressed dorsoventrally, its length 1.21 transdiameters; girdle submedian, 

 displaced about twice its own width; sulcus extending from girdle to antapex; 

 strontium yellow chromatophores. Length, 31m. Pacific off La Jolla, California, 

 July, August. 



Description. — The body is broadly ellipsoidal, almost globular in shape, with broad apices, 

 its length 1.21 transdiameters at the widest part. It is slightly compressed dorsoventrally, its 

 dorsoventral diameter being 0.93 transdiameter. The hypocone slightly exceeds the epicone in 

 length. The epicone is hemispherical with smoothly rounded sides and broad apex. It has a 

 length on the left and right sides of 0.28 and 0.41 respectively of the total length of the body. 

 The hypocone also has a hemispherical outline with broad antapex slightly or not at all inter- 

 rupted by the sulcal notch. 



The girdle is slightly premedian in position. Its proximal end meets the sulcus at a distance 

 from the apex of about 0.28, and its distal end 0.41 of the total length of the body. Its path 

 around the body is that of a descending left spiral, with its distal end displaced pasteriorly 

 about twice its own width. The furrow is wide, about 0.06 transdiameter. but somewhat unequal 

 throughout, and is deeply impressed. The furrow undercuts the anterior lip, gradually curving 

 out posteriorly to meet the surface of the body. The .sulcus rarely or never extends upon the 

 epicone. It extends posteriorly to or near the antapex as a slightly sinuous line. Its width 

 appears to be irregular. The left border projects more or less above the general surface and 

 frequently forms an overlap partly covering the trough. This slightly raised appearance of 



