KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 369 



This species is generally seen in chains of two or four individuals within a pyriform trans- 

 lucent gelatinous cyst whose length is about five times that of the body. Sehiitt figures this with 

 the broader end posterior in his earlier paper (1895) and anterior in the later one (1S96). 

 After treatment with safranin the cyst sliows granular concenti'ic laminations surrounding a 

 non-laminate axial region containing the chain. 



DiMFA'SiONS. — Length, 47-75/^; transdiameter, 35^5^; axes of nucleus, 22/^ 

 and 30/t; length of cyst, 185/^; diameter, 108/^. 



OccuBRENCE. — Taken on two occasions in the plankton off La JoUa, Cali- 

 fornia, in 1906, once on July 3, 2.75 miles offshore in a haul of a No. 20 net 

 from 185 meters to the surface in a surface temperature of 20?4: C, and again 

 on July 10 in a surface haul of a No. 12 net, 2 miles offshore in a surface tem- 

 perature of about 20-9 C. In Ijoth instances chains of four individuals were 

 found. On July 10 the species was fairly abundant. 



Sehiitt (1895) figures it presumably from the Bay of Naples or from the 

 collections of the Phmkton Expedition in the Atlantic. It has not been reported 

 elsewhere. 



Activities. — The individuals, both free and in chain, rouitd up and e}i:olize 

 quickly. Individuals in chain frequently separate when stimulated by the 

 illumination of the microscope. When this occurs in a cyst the remnants will 

 fuse into a single sphere. As c^'tolysis approaches the surface is wrinkled 

 locally by waves of contraction producing pseudopodia-like elevations. The 

 pellicle becomes detached locally after these contractions, a clear fluid oozes 

 out at the flagellar i)ores, along the furrows and elsewhere, and when the pellicle 

 al)oiit the noAV spheroidal mass ruptures the cytoplasm flows out and is speedily 

 dissolved. 



CoMPAEisoNS.- — Too little is critically known of this species for comparisons. 

 It is not far from C. constpiratHW (fig. GG, 10) on the one hand and C. cate- 

 natiim (fig. GG, 14) on the other. The latter tends to form chains, but is 

 smaller, a])pears to have less torsion, 0.5 turn only, and less intercingular dis- 

 placement, 0.6 instead of 0.8 total length, and to be nearly colorless instead of 

 having ochraceous chromatophores. C. geminatum is more elongated and less 

 incised than C. conspiratum and has chromato])liores, which the latter lacks. 

 Note should be made of the fact that the more elongate individuals with two 

 turns of the girdle which Sehiitt (1895, pi. 23, fig. 75:,) figtires are very close to 

 C. archimedes (Pouchet) Lenmi. (fig. HH, 17) in size, proportions, and torsion, 

 and should be classed with it were it not for the implication which Sehiitt 's 

 (1896) later figure raises, that it is a phase of the chain of his other figure 

 (fig. 75^) in which prior to fission the torsion has increased 0.5 turn and the 

 airdle and sulcus have elongated considerablv. It is the least distorted member 

 of the C. distortum group of the subgenus GJ!)))liodinium and might equally 

 well be placed in the C. citron group of the subgenus Cochlodininm. 



Syxoxy^fy. — This species was figured by Sehiitt (1895) as Gi/nuiodiiiiii))i 

 geminatum, but noted later by him (1896) as a Cochlodinium. 



