KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 259 



The nucleus is an ellipsoidal body filled with coarse, moniliform chromatin strands. It is 

 found in the anterior half of the body. Its major and minor axes are about 0.49 and 0.29 

 transdiameters in length i-espectively. The greatly elongated nucleus in figure 42, plate 4. is a 

 predivision stage. 



Small, saeklike pusules may open into either or both flagellar pores. The cytoplasm is very 

 finely granular, clear and transparent. The body usually contains numerous food masses and 

 small refractive granules. The presence of long, slender green rodlets is common in many 

 individuals. In text figure AA, 9, the posterior part of the body is filled with a very large food 

 body. Nutrition is holozoic. A distinct ectoplasm can be observed in most of the specimens. 

 This is most conspicuous on the surface which exhibits the same undulations found in G. 

 pacltydcrmatum. The general color of the organism is pale cendre green shading to yellow 

 ochre. No striae or other markings could be detected on the surface. 



Dimensions. — Length, 47i«. to 68^*; trausdiameter, 40/* to 47/*; axes of nucleus, 

 10/* and 10/*. 



Occurrence.— This Avas figured by Calkins (1902) from the Atlantic off 

 Woods Hole, Massachusetts, July, August. It was first seen in the Pacific at 

 La Jolla, California, July 18, 1906, in a surface haul made with a No. 20 net. 

 On July 20 it was again taken tmder the same conditions. During July and 

 August, 1917, it was frequently met in the surface hauls made at the end of the 

 ]uer at the Biological Station and in a number of the deep hauls made farther 

 offshore. The number of individuals o])served in one haul varied from one to 

 three. A thin, double-contoured cyst enclosed many of them when first observed. 

 In one specimen noted two individuals were enclosed in one cyst, probably the 

 resulting products of division. 



Co2*iPARisoNS. — This species l)elongs in the subgenus Pachijdiuium because 

 of the presence of a thickened ectoplasm. Its color, greenish yellow, is that 

 common to many of the species in that subgenus. It does not, however, show 

 the highly differentiated ectoplasmic structure found in G. pachijdennatum 

 sp. nov. (fig. AA, 5), but more nearly approximates the condition in G. situin 

 sp. nov. (fig. Z, 6) and, perhaps, G. tonds.siniK})! sp. nov. (fig. AA, 7). Its 

 smaller size and rotund ovoidal body clearly distinguish it from other species. 



Synonymy. — This species was figured by Calkins (1902) as G. gracile var. 

 sphaerica. It differs from G. grucUc, however, in its lack of surface striae, size, 

 proportions, and in its type of ectoplasmic differentiation, and is tints specifically 

 distinct rather than subspecifically. 



Gymnodinium sulcatum s]). nov. 



Plate 8, figure 83 ; text figure X, 1 



Diagnosis. — A meditun sized species with broad, rotund ovoidal body, its 

 length 1.05 transdiameters; girdle submedian without displacement; sulcus ex- 

 tending from apex to antapex; hypocone sparsely ribbed; color, dull rose red. 

 Length, 63/*. Pacific off La Jolla, California, August. 



Description. — The body is rotund, its length and trausdiameter nearly equal, widest at the 

 middle, narrow anteriorly and broad posteriorly. In cross-section the body is nearly circular. 

 The epicone and hypocone are suhccjual in size. The epicone is subconieal in shape with an 

 angle of about 80 \ The sides are convex, the left one slightly sigmoid in outline, with scarcely 



