KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 385 



siuistroventral face of the body. It is less deeply impressed ou tlie dextrodorsal surface. Its 

 width is 0.08 transdiameter. The anterior flagellar pore opens at the anterior junction of the 

 girdle and sulcus, the posterior pore at the posterior junction. 



The sulcus invades the epicone in a short, curved extension which terminates near the apex. 

 It passes posteriorly in the hollow of a very deep trough, making 0.50-0.65 turn before meeting 

 the distal end of the girdle. Beyond the distal junction it widens to about twice its width above, 

 and terminates on the left side of the median line at or near the postmargiu, sometimes with a 

 slight sulcal notch. Its total length anteroposteriorly is about 0.9 of that of the body. 



The nucleus is spheroidal to ellipsoidal and located in the posterior half of the body. About 

 ten moniliform chromatin strands traverse it spirally about its main axis. Its axes vary in 

 length from. 0.40 and 0.32 to 0.5 and 0.3 transdiameter respectively. 



A large sacklike pusule opens distally into each flagellar pore. In one individual their 

 proximal ends were connected, forming a complete channel between the two pores. The pusules 

 are filled with a pale pinkish fluid. The cytoplasm is exceedingly clear and transparent, with 

 no granular structure discernible. It usually contains from one to several food masses of 

 ochraceous or greenish color. In the anterodextral part of the body is a large reniform, greenish 

 or oil-yellow vacuolated body which seems to be a food mass. Eveiy individual observed there- 

 after, however, contained this same body in about the same location. Its length is 0.80 to 0.85 

 transdiameter and its diameter about half its length. Its periphery is wholly covered with 

 small, highly refractive spherules resembling oil drops of uniform size, arranged with consid- 

 erable regularity. Its center contains an elongated pinkish vacuole, and in one instance what 

 appears to be a nucleus of the dinoflagellate type is indicative of cannibalistic tendencies. No 

 striations or other markings could be detected on its surface. The color is a pale glaucous blue. 

 In the peripheral zone were a number of gi-eenish spherules, probably oil droplets, and in one 

 individual there was a peripheral zone of shoi-t radial rhabdosomes, faintly tinged with orange 

 or yellow near the apices in some individuals. 



Dimensions. — Length, 50-75/^; transdiameter, 36-63i^; diameter of iiuclens, 

 ]7m, or with a major and minor axes of 19-30/* and 15-19/* respectively. 



Occurrence. — The first individual was taken July 9, 1917, with a No. 25 

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

 in a surface temperature of 19°8 C On July 11 a second individual was taken 

 under similar conditions in a surface temperature of 20-2 C. On July 20 it 

 was again taken in a haul made 6 miles offshore, in a similar haul in a surface 

 temperature of 21° C. A fourth individual was taken on August 10 in a haul 

 from 50 meters to the surface, one mile offshore, in a surface tem])erature of 

 22?5 C. 



Activities. — When first placed under the cover glass this species is exceed- 

 ingly active, incessantly on the move, circling mainly in close clockwise spirals 

 only several lengths of the body in diameter. In about thirty to seventy minutes 

 it slows down, rounds up, and undergoes cytolysis. It is pi'one to fasten itself 

 to the slide by the anterior end, presumably the region of the anterior junction 

 of the girdle and suknts. It often circles for a long time without rotation of 

 the body on its axis. 



COi\rPAHTsoNS. — This species belongs to the C. distortion series in the sub- 

 genus (llijphodinium, and lies midway between G. rosaccum (fig. HH, 4) and 

 C. convohdum (fig. HH, 5). Its ventral excavation is much less than in C. 

 cavatum (fig. HH, 10), its torsion is greater and its displacement of girdle less, 



