KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 321 



Gyrodinium ochraceum sp. nov. 



Plate 7, figures 76, 82; text figure DD, 17 



DiAGXosis. — A large species Avith btillet-sliaped body, its length 2.28 trans- 

 diameter; girdle a descending left spiral with overhang of 0.4 transdiameter 

 and dis])la cement of 1.04 transdiameters ; snlcns extending from apex to antapex 

 in a left spiral of 0.5 turn ; surface striate ; color, ochraceous orange. Length, 

 123/*. Pacific off La Jolla, California, July. 



Description. — The body is of robust habit, circular in cross-section ; bullet-shaped with 

 pointed anterior end, rounded posteriorly, its length 2.28 transdiameters at the widest part 

 which is postmedian. The sides may be subparallel (pi. 7, fig. 76) or the dorsal surface may be 

 convex and the ventral concave (pi. 7, fig. 82). The epieone and hypocone are subequal in size, 

 though the greatest length of the ejiicone exceeds that of the hypocone by 0.24 of its own lengtli. 

 The epieone is elongate conical in outline, about 60° above the anterior pore, with convex sides 

 and pointed apex. Its length on the left of the sulcus is about 0.35 and on the right is 0.87 of 

 the total length of the body. Along the girdle it flares out abruptly into a narrow shelflike 

 projection. The hjpocone is dome-shaped with broadly rounded antapex. Like the epieone it 

 forms a narrow, shelflike projection along the posterior border of the girdle. There is no sulcal 

 notch at the postmargiu. 



The junction of the girdle and sulcus occurs at a distance from the apex of about 0.35 of the 

 total length of the body. It forms a descending left spiral which is displaced posteriorly on the 

 right side about 1.04 transdiameters. with an overhang of about 0.4 transdiameter. It lies in a 

 wide, deep depression with wide overhanging, shelflike bordei-s. The anterior flagellar pore is 

 located at the anterior junction of the girdle and sulcus and the posterior pore midway between 

 the pcsterior junction and the antapex. 



The sulcus begins at or near the apex and extends to the antapex in a spiral course. Below 

 the anterior pore it widens, contracts just above the distal junction and posteriorl.y expands into 

 a wide trough which reaches the antapex, making 0.5 turn of a left spiral to the opposite face. 

 It lies in a deep depression with high, smootlily rounded borders. 



The nucleus is subspherieal or slightly ellipsoidal and located in the middle regions on the 

 right side of the body. It is tilled with coarse, moniliform chromatin strands. Its axis is 0.5 

 transdiameter in length. 



A long pusule, variously lobed and branched, opened into both flagellar pores, the expanded 

 portions being connected by a long slender canal. The cytoplasm is clear and transparent and 

 yellowish grey in color. Food inclusions of any kind Avere extremely rare in all tlie individuals 

 of this species observed. The surface is finch' striate with equidistant blue-green lines. These 

 are about 2/u, apart at the girdle, about 25 across the ventral face, and are approximately equal 

 in number on epieone and hypocone. The general color of the body is .yellow green with 

 ochraceous-orange granules thickly scattered in the surface cytoplasm. This colored pigment 

 possesses remarkable powers of amoeboid activity. In the first specimen observed it was collected 

 in rounded graiuiles scattered thickly over the surface with a ma.ss in the apical region (pi. 7, 

 fig. 76). Later these became grouped on the dorsal surface and along the r(>gion of tlie girdle, 

 forming a wide band similar to that observed in another individual. The second individual was 

 found in the same material with the color massed in a long baiuUike zone with irregular margins, 

 following the girdle around the body. After an hour and a half on the slide undci' observation, 

 the edges of the band became more ragged and small particles were pinched ofif. These rounded 

 up and moved out over the surface. Two hours later the entire pigment ma.ss had thus become 

 broken up into snudl granules evenly distril)uted over the body. Another individual was observed 

 in w hieh the small pigment granules were in the act of becoming agglomerated along the girdle 

 into one long band. 



