KOFOID AND SWEZY: UNARMORED DINOPLAGELLATA 223 



Synonymy. — Dogiel (1906) described, as Gymnodinium spirale var. obtnsum 

 S^'hiitt, a form idoutieal with our species. Sehiitt's organism (1895) of tliat 

 name, however, is a Gijrod'nuum, and not the same as Dogiel 's form. We tliere- 

 fore place the latter with our species as Gijmnodinium heterostriatuni nom. 

 sjD. nov. 



Gymnodinium incisum sp. nov. 



Plate 3, figure 27 ; test figure X, 33 



Diagnosis. — A small species with rotund body, its length and transdiameter 

 equal; girdle a submedian, descending left spiral, displaced 0.19 transdiameter; 

 sulcus extending from near a])ex to antapex; color, oil yellow. Length, 52m. 

 Pacific off La Jolla, California, August. 



Description. — The body is rotund, rounded anteriorly, deeply notched posteriori}', its length 

 equal to its widest transdiameter. The epicone and hypocone are subequal, their greatest lengths 

 being the same. The epicone is hemispherical in outline with a slight irregularity in its contour 

 at tlie apex, tending towards the formation of a low point or peak. The sides are smoothly 

 rounded. In cross-section the shape is nearly circular with only a slight flattening on the mid- 

 ventral surface. It has a length on the left and right sides of 0.34 and 0..55 respectively of the 

 total length of the body. The hypocone has more steeply sloping sides than the epicone and its 

 greatest transdiameter is slightly less. The antapex is narrower than the apex, its sides smoothly 

 rounded with a deep central excavation foi-med by the distal end of the sulcus. This produces 

 two lobes in ventral view, each having a length of about 0.09 of the total length of the bod}^ 

 Anteriorly the sides of the hypocone flare out in a broad shelflike border to the girdle. 



The girdle is slightly prcmedian in position for the greater part of its length. Its proximal 

 end joins the sulcus at a distance from the apex of 0.34 and its distal end at 0.55 of the total 

 length of the body. Its course is that of a descending left spiral with the distal end displaced 

 posteriorly 0.19 transdiameter. The furrow is wide, about 0.05 transdiameter, and is deeply 

 impressed. Its borders are raised slightly above the surrounding surface of the body. 



The sulcus invades the epicone as a shallow trough which is deflected to the right at an angle 

 of about 42° with the median longitudinal plane of the body. It fades out when slightly moi-e 

 than midway of the distance from girdle to apex. After meeting the proximal end of the girdle 

 it turns and passes in a nearly straight line to the antapex. The trough widens at the anterior 

 pore and deepens posteriorly until, in the antapical region, its depth becomes equal to the dorso- 

 ventral diameter at that plane. It cuts the dorsal surface of the body, forming two lateral lobes 

 separated by a deep excavation at the antapex. The anterior pore opens at the proximal junction 

 of the girdle and sulcus, the posterior pore about midway between the distal junction and tlie 

 antapex. 



The nucleus is a large body, ellipsoidal willi sliglitly concave sides. It is found in llie left 

 anterior part of the body with its long axis diagonal to the long axis of the body. It is filletl 

 witli coarse chromatin strands. Its major and minor axes are about 0.57 and 0.34 ti'ansdiameter 

 respectively in length. 



A small sacklike pusule opens into each flagellar pore. The cytoplasm is finely granular and 

 contains an abundance of minute green oil droplets scattered through the peripheral zone. 

 Nutrition is holozoic, as indicated by the presence in the body of an ingested Pouchctia, probably 

 /-". ruhesccns. This had been partly digested, its Indian-red color still noticeable and its ocellus 

 conspicuous. The general color of the organism is oil yellow witli a peai-1 grey background, the 

 general elfect quite rich. 



