312 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA 



Diagnosis. — A minute species with asymmetrical, ovoidal body, its length 

 1.36 transdiameters ; girdle a descending left si^iral. displaced 0.35 transdiam- 

 eter; sidcus extending from girdle to antapex; no chromatophores. Length, 

 23.6/^. Fresh-water ponds in the Botanical Gardens at Basel, Switzerland. 



Description. — The body is irregularly ovoidal and widest in the middle, \sitli broadly rounded 

 but asymmetrical apices, its length 1.36 transdiameters at the widest part. The hypocone exceeds 

 the epicone in extent, its length being greater by 0.27 of its own length. The epicone is broadly 

 rounded at the apex and has a length on the left and right sides of 0.17 and 0.44 respectively 

 of the total length of the body. It is oblique upon the right side. The hypocone is hemispherical 

 in outline in the posterior half, with broad antapex, but slightly oblique upon left side. 



The left side of the girdle is placed far anteriorly, meeting the sulcus at 0.17 of the total 

 length of the body from the apex. It passes transversely around to the dorsal side, where it 

 turns posteriorly in a descending left spiral course, displacing the right side of the girdle 0.35 

 transdiameter. The furrow is wide, about 0.23 transdiameter, and is deeply impressed with wide, 

 overlianging borders. Its anterior border on the right side of the body projects considerably 

 beyond the posterior lip and is less rounded. The sulcus extends from the middle of the ventral 

 side to the posterior end of the body, but its position is not shown in Schilling's (1891f;, h, 1913) 

 figures. The transverse flagellum traverses the entire length of the girdle, arising presumably 

 at the proximal junction of the girdle and sulcus. The longitudinal fiagellum arises slightly 

 behind the distal end of the girdle. 



Nucleus and pusules are not figured by Schilling. A small carmine-colored stigma is present 

 in the suleal region near the origin of the longitudinal flagellum. Nutrition is holozoic. Schilling 

 (1891&, pi. 10, figs. 5-7, 9-22) has described a process of food taking for this species, in which 

 amoeba-like pseudopods are formed to aid in the ingestion of small organisms. Unfortunately, 

 however, the connecting links between the Gymnodinium hyalinum and the amoeba-like forms 

 are lacking in his figures. 



DiMExsioxs. — Length, 23.6m; transdiameter, 20. 7m, as given in the text 

 (Schilling, 1891ff, h, 1913). A careful measurement of his figure, however, 

 gives the transdiameter as 17. om. In the description above we have used the 

 latter measurement. 



OccuRRExcE. — Figured by Schilling (1891a) from fresh- water ponds in the 

 Botanical Gardens at Basel, Switzerland. 



Syxoxymy. — Originally described by Schilling (1891) as G}j})inodinium 

 hi/ali)u())i, this species was later transferred l)y Lemmermann (1900, 1903) to 

 S pi rod i niton. Schilling (1913) later accepted this allocation in his monograph 

 of Gennan fresh-water dinofiagellates. 



CoMPARisoxs. — This species and G. pusillnni form the only fresh-Avater 

 representatives in the genus. They greatly resemble each other in the position 

 of girdle, size, and shape. G. lii/alinxni lacks the chromatophores present in 

 G. 2^11 sill urn. 



Gyrodinium intortum sp. nov. 



Text figure CC. 10 



DiAGxosis. — A small species with broadly ellipsoidal body, its length 1.37 

 transdiameters; girdle a descending left spiral, displaced 0.4 transdiameter, 

 vnth an overhang of 0.6 transdiameter ; sulcus with antapical loop and torsion 

 of 1 turn ; color, green. Length, 62m. Pacific off La Jolla, California, July. 



