KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 267 



Dimensions. — Length, 47/^; traiisdiameter, 15m; nucleus, 6/* by 5/*. 



Occurrence. — This species was figured hy Schiitt (1895) from the collec- 

 tions of the Plankton Expedition from the Atlantic or from the Mediterranean 

 at Naples. It is also recorded by Lohmann (1908, 1911) from the Baltic Sea 

 off Kiel, Germany, where he found it throughout the yesLV, reaching its maximum 

 in August. Ostenfeld (1913) observed it in the Cattegat. 



ro:NrrARisoNS. — Among striate species included in the suligenus Lincadininm 

 this species presents the maximum relative enlargement of the hypocone at the 

 expense of the epicone. A tendency in this direction is detected in G. aureum 

 sp. nov., G. uclirouKiticiDii Le])Our, G. attcnuatum sp. nov., G. gracile Bergh, 

 G. abhreviation sp. nov., and G. puniccuni sp. nov. (figs. Y, 3, 8, 12; figs. Z, 3, 

 7, 5). The limitation of striae to the hypocone is similar to that in G. herbaceum 

 Kofoid (fig. Y, 17). The species is a very aberrant one, widely divergent from 

 the others in the genus. 



Gymnodinium violescens s}). nov. 



Plate 6, figure 69 ; text figure X, 11 



Diagnosis. — A small species ^\'ith biconical body, its length 1.42 transdiam- 

 eters ; girdle submedian, displaced about 3 tunes its own width ; sulcus extending 

 from girdle to antapex ; color, pansy violet. Length, 60/*. Pacific off La Jolla, 

 California, July. 



Description. — The body is asymmetrical, biconical, almost rhomboidal, with rounded apices, 

 its length 1.42 trausdiameters at the \videst part. Its dorsoventral and transdiameter are equal 

 in length. The epioone and hypocone are subequal in size. The epicone has the general shape 

 of a cone of about 80°, with broad, blunt apex. The left side of the base of the epicone is consid- 

 erably higher than the right, but the sides are equal in length, throwing the apex to the right of 

 the midplane of the body. The sides are slightly concave posteriorly and convex anteriorly. 

 The epicone has a length on the left and right sides of 0.43 and 0.58 respectively of the total 

 length of the body. The hypocone has the shape of a cone of about 65°, the left side of which is 

 about 0.02 longer than the right. Both sides have a greater convexity than those of the epicone. 

 The ventral surface is deeply grooved by the broad sulcus. 



The girdle is submedian. its proximal end meeting tlie sulcus at a distance from the apex of 

 0.43 and the distal end of 0.58 of the total length of the body. It forms a left-wound spiral, the 

 first half of the course taking a transverse or slightly anterior direction, the second half turning 

 posteriorly with its distal end displaced about 0.25 transdiam(>ter. The furrow is wide, about 

 0.07 transdiameter, and deeply impressed. The anterior border is undercut by the furrow which 

 curves gradually outward to the posterior border. The borders are outlined l)y lines of bright 

 yellow green. 



The sulcus begins at the pi-oximal end of tlie girdle and extends posteriorly to the antapex. 

 The trough is about equal to tlie girdh' in width anteriorly. Beyond the junction with the distal 

 end of the girdle it becomes broader and deeper, the left side being deflected so \videly that it 

 becomes lost near the lateral l)order of the body in ventral view. The riglit side is deflected to 

 a less extent, reaching a point nearer the antapex before fading out. The anterior flagellar pore 

 opens at the proximal end of the girdle, tlie posterior pore about two widths of the girdle behind 

 the distal end. 



