150 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA 



CoMPAEisoxs. — This is the only one of the larger species of AynpMdinium 

 which possesses the small leaflike chromatophores such as are fonncl in .4. 

 dcntatum and ^4. gaJhnnnm (figs. U, 4, 29). 



Amphidinium rotundatum Lohmann 



Text figure U, 22 



Amphidinium rotundatum Lohmann (1908), pp. 147, 199, 202, 254, 261, 324, table B, pi. 



17, fig. 9; (1911), pp. 30, 31, fig. 12c, pi. 1, fig.5 

 A. rotundatum, Paulsen (1908), p. 95, fig. 129. 

 A. rotundatum, Herdman (19116), p. 71; (1911c), p. 38. 

 A. rotundatum, Schiller (1911), p. 31. 

 A. rotundatum, Mielck (1914), p. 20. 

 A. rotundatum. Ostenfeld (1913), p. 338. 

 A. rotundatum, Lemmermann (1910), p. 615. 



Diagnosis. — A minute species with broadly ovoidal body, its length 1.2 trans- 

 diameters ; epicone very minute ; yellow chromatophores. Length, 12^^. Baltic 

 Sea off Kiel, Germany. 



Description. — The body is broadly top-shaped, the narrow neck and head formed by the 

 girdle and flat epicone tapering posteriorly to a blunt antapex. Its length is 1.2 transdiameters 

 at the widest part. The girdle is broad, about 0.25 transdiameters, and deeply constricts the 

 anterior part of the body to 0.5 of its width behind the girdle. Sulcus not known. The flat 

 epicone also has a width of 0.5 transdiameter and no appreciable length. The most striking thing 

 about this organism is the yellow, leaflike chromatophores located in the peripheral layer of the 

 cytoplasm. 



Dimensions. — Length, 12/*; transdiameter, 10m. 



Occurrence. — Figured by Lohmann (1908) from the Baltic Sea off Kiel, 

 Germany, present throughout the year. Mielck (1914) records its presence in 

 the Barents Sea and White Sea near Kola, Russia, in June and July. 



Amphidinium scissum sp. nov. 



Plate 2, figure 22; text figure U, 1 



Diagnosis. — A small species with ovate body, compressed dorsoventrally to 

 0.5 transdiameter, wider posteriorly; epicone flattened, higher at the right; 

 h}7)ocone deeply notched at antapex; girdle displaced posteriorly 0.24 trans- 

 diameter ; sulcus runs from apex to antapex ; color greenish ; food inclusions 

 often present ; littoral habitat. Length, 56/^. Pacific at La Jolla, California, 

 July. 



Description. — The body is ovate, its greatest transverse diameter 1.7 to 1.8 transdiameters 

 at its widest part, which is slightly below the middle, compressed dorsoventrally to little less than 

 0.5 the greatest transdiameter. Its length is about 3 transdiameters measured in the girdle. The 



