KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 221 



CoMPARisoxs. — This species comes closest in its general size and proportions 

 to G. mveuesccus. It differs from it, however, in its striate snrface and in its 

 chromatophores. That it is holozoic in nutrition might be inferred from the 

 number and size of fluid-filled vacuoles i)reseut. In this i-espect it recalls the 

 conditions figured by Stein (1883, pi. 17, figs. 14-16) for Amphidinium steini. 

 This species possesses chromatophores, yet is capable of ingesting smaller 

 organisms {G. ravencscens and G. flavesccns also exhibit indications of holozoic 

 nutrition). It belongs to the subgenus Gymuodinium, but in the presence of 

 few striae on its surface it inclines towards the next subgenus, Lineadinium. 

 Clu-omatophores are relatively rare in the subgenus Gymnodinium, being 

 possessed l)y only a few small forms, mostly fresh-water in habitat. 



Gymnodinium heterostriatum nom. sp. nov. 



Plate 2, figure 24 ; plate 5, figure 56 ; text figure Y, 7 



Gymnodinium spirale var. obtusum Dogiel (1906), pp. 38--13, pi. 2, figs. 50-56. 

 G. spirale var. ohtusum, Entz, Jr. (1907), p. 17; (1909), p. 254. 

 G. spirale var. obtusum. Klebs (1912), p. 430. 



Diagnosis. — A medium sized species with symmetrical ellipsoidal body, its 

 length 1.5 transdiameters ; girdle submedian, displaced its own width; sulcus 

 extending from apex to antapex ; surface heterostriate ; color pinkish cinnamon. 

 Length. 67m. Pacific off La Jolla, California, June to August; Gulf of Naples, 

 ]May to July. 



Description. — The body is of robust habit, varying in shape from broadly ellipsoidal to 

 bieonical or ovoidal with broadly rounded apices, its length about 1.5 transdiameters. It is 

 nearly circular in cross-section. The epicone and hypocone ai'c subequal. The epieone is broadly 

 dome-shaped with broad, rounded apex. It has a length on the left and right sides of about 0.52 

 and 0.59 respectively of the total length of the body. The hypocone is subconieal, about 50", 

 with rounded sides and blunt apex. It is usually slightly less in transdiameter than the epicone, 

 ydih narrower antapex. 



The girdle is submedian, its proximal end joining the sulcus at a distance from the apex of 

 0.52 of the total length of the body. It forms a descending left spiral, its di.stal end joining the 

 sulcus at a distance from the apex of 0.59 of the total length of the body, being displaced about 

 its own width accompanied by a slight overlapping. It usiuilly exhibits a slight sigmoid curve 

 at its proximal end, in the lower curve of which opens the anterior flagellar pore. The furrow 

 is wide, about 0.08 transdiameter, and deeply impressed, its upper lip slightly raised and cut 

 under almost horizontally, while the lower one is more gradually curved. The borders are 

 marked by a double-contoured line usually blue green in color. The sulcus is very narrow and 

 extends in a sinuous line from the apex to the antapex. It becomes very shallow on the hypocone 

 and fades away near the antapex. The posterior flagellar pore is found a short distance posterior 

 to the distal junction of the girdle and sulcus. 



The nucleus lies slightly anterior to the center and somewhat to the right side. It is nearly 

 circular in outline. In one individual under observation the circular nucleus changed after 

 about 40 minutes to a reniform shape with a distinct hollowing out, the concavity being occupied 

 by a granular body recalling the dumbbell-shaped centrosphere or paradesmose of Noctiluca 

 (Ishikawa, 1894, Calkins, 1901, and Doflein. 1911). ]\ntosis was not accomplished prior to 

 dissolution. The axis of tlie nucleus is about 0.43 transdiameter in length. 



