KOFOID AND SWEZY: UNARMORED DINOPLAGELLATA 227 



green. Standing out in relief against tliis is the pomegranate-purple coloring matter or pig- 

 ment, located in the peripheral zone, immediately beneath the tliin ]X'rii)last. Tliis is amoeboid 

 in eliaraeter and changes its shape and position so rapidly that it is impossible to obtain a 

 complete camera drawing of its appearance at one time. On the epicone it is located in stout 

 rods linearly arranged, on the hj'pocone in irregular masses held in a coarse netwoi'k of the 

 same material. The dorsal location of this color was only a temporary localization. Wlien 

 first observed it was spread over a greater portion of the body. The surface was free from 

 striations or other markings, but the pigment localization on the epicone strongly suggests a 

 fundamental tendency in the direction of the linear organization of subpellicular substance in 

 parallel equidistant lines. 



Di:\[Exsioxs. — Length, 78/*; transdiamcter, 70/*; axes of nucleus, 21m and 15/*. 



OccuEREXCE. — This species was represented by a single individual in the 

 materia] under oljservation. It was taken August 8, 1917, with a No. 25 net 

 in a haul 4 miles off La Jolla, California, from 80 meters to the surface and in 

 a surface temperature of 22?5 C. 



CoiMPAEisoxs. — This is one of the most strikingly colored species of Gi/mno- 

 dinium. It is unique, also, in the extreme mol)ility of the " chromatophores, " 

 if one may so term the color masses. This mobility resembles the condition 

 exhibited by the color masses in Gyrodinium ochraceum (])1. 7, figs. 7G, 82), and, 

 perhaps, in Eri/tJi ropsis scarlatina. In the latter species, liOAvever, active move- 

 ment of the pigment mass was not observed, but its appearance suggested the 

 probability that it takes place. The striate arrangement of the color on the 

 epicone and the total lack of stich arrangement on the h,ypocone suggests a 

 fundamental tendency towards striate organization in the cytoplasm of that 

 region similar to that in G. contractuw. 



This species is unique in GijiiuiodiiiiiDii in the proportions of epicone and 

 hypocone, resulting in a balloon-shaped body, further marked off by its promi- 

 nent purple color pattern. It is one of the most highly specialized and widely 

 divergent types found in the subgenus Gymnodinium. The possibility that its 

 hypocone may be modified in form by the recent discharge of a large food body, 

 and that the color has been, in i^art at least, derived from, or modified by, the 

 food previously digested is not precluded. 



Gymnodinium lira s}). uov. 



Plate 3, figure 30; text figure Z, 11 



Di.\axosis. — This is a large species with rotund, ellipsoidal l)ody, its length 

 1.47 transdiameters ; girdle premedian, displaced al)out twice its own width; 

 sulcus, extending from apex to antapex; surface ribbed; color, grey green. 

 Length. 103/*. Pacific off La Jolla, California, June, September. 



Description. — The body has a rotund habit, widest in the midille witli broad, rounded apices, 

 a cross-section nearly circular in outline, its length 1.47 transdiameters at the widest part. The 

 hypocone exceeds the epicone in size, being longer In- 0.26 of its own length. The epicone is 

 dome-shaped, or convex conical, flaring slightly at the girdle, with broad rounded apex. The 



