300 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA 



makes the orientation of this species a tentative one only. We have, however, 

 followed, in our description, the orientation given in Schiitt's figure 81i. 



CoiNiPAEisoxs.— This is one of the four species of Gifrodiuiiim showing the 

 presence of chromatophores, the other species being G. piisilhim (Schilling), 

 G. melo sp. nov., and G. foUaceum sp. nov. (figs. CC, 3, 9, 18) . The yellow-ochre 

 chromatophores of this species are similar to but smaller and more numerous 

 than those in Gijmnodhnvm fiisus. The presence of small globules or vacuoles 

 throughout the cytoplasm suggest holozoic nutrition, as these are probably 

 p]-oducts of metabolism. In its contracted apices this species is unique in 

 Gyrodinium. 



Gyrodinium fissum (Levander) 

 Plate 9, figure 95 ; text figure DD, 8 



Gymnodinium spirale var. D Pouchet (1883), p. 448, fig. K. 



G. fissum Levander (1894a), pp. 43-.50, pi. 2, figs. 5-20; (18946), p. 210; (1900), p. 41; 



(1901a), pp. 8, 13, 18, 19; (19016), p. 6; (1913), p. 36 (as Spirodinium fissum). 

 Spirodinium fissum, Lemmermami (1900), p. 116; (1901), p. 359; (1905a), p. 20. 

 8. fissum, Paulsen (1908), p. 101, fig. 139. 

 Gymnodinium fissum, Ostenfeld (1908), pp. 136, 162, 210, 213. 

 Spirodinium fissum. Lebour (19176), p. 193. 



Di.\Gxosis. — A small species with subovoidal or ellipsoidal lx)dy, its length 

 1.79 transdiameters ; girdle a descending left spiral displaced 0.31 transdiam- 

 eter ; sulcus extending from apex to antapex ; surface finely striate ; color, pale 

 Veronese green. Length, 46/*. Pacific off La Jolla, California, July, August ; 

 Atlantic off Concarneau, France ; Gulf of Finland. 



Description. — The shape of the body is subovoidal to ellipsoidal, .somewhat metabolic poster- 

 iorly, its length 1.79 tran.sdiameters at the widest part, which is at the girdle. A cross-section 

 of the body is nearly circular in outline. It is rounded at both apices, but usually more tapering 

 anteriorly or the two may be subequal. The epicone exceeds the hypocone in size, its length being 

 greater by 0.22 of its own length. The epicone is rounded dome-shaped, somewhat less than a 

 hemisphere, with broad, synunetrically rounded apex. The relative length and width vary 

 considerably in different individuals; when well extended it is subconical with slightly rotund 

 sides. As the contraction of the body increases the convexity of the sides becomes more pro- 

 nounced and the altitude decreases. It has an average length on the left and right sides of 0.4 

 and 0.67 respectively of the total length of the body. The hypocone is slightly broader than the 

 epicone with broad, rounded antapex, or it may be eqiial or slightly narrower with the right side 

 of the antapex extending farther posteriorly than the left side. 



The girdle is submedian in position, its proximal end joining the sulcus at a distance from 

 the apex of 0.4 of the total length of the body. It forms a descending left spiral with its distal 

 end joining the sulcus at a distance from the apex of 0.67 of the total length of the body, its 

 displacement being about 0.31 transdiameter. The greater part of this displacement takes place 

 in the distal fourth of the girdle where it follows a course at an angle of about 45° with the 

 median longitudinal plane. The first part of its course is in a nearly transverse direction around 

 the body. The furrow has a width of about 0.08 transdiameter and is deeply impressed with 

 smooth borders, of which the anterior one is deeply undercut. Both borders are usually raised 



