392 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA 



on tlie anterior are of a complete circle. Scattered through the cytoplasm are numerous highly 

 refractive spherules filled with a glaucous gi-een fluid. Schiitt (189.5) figures a layer of per- 

 ipheral radial rhabosomes in regions where there are no chromatophores (?). There is no 

 evidence that this organism is holozoic, neither is the color of the "chromatophores" or rhab- 

 dosomes conclusive of holophytic nutrition. 



There are no striae on the surface. The general color of the plasma is a pale Veronese green. 

 Rhabdosomes or chromatophores and nucleus alike round up, as cytolysis approaches, and the 

 body itself also foreshortens and rounds up till its transdiameter is half its length. 



DiMEXsioxs. — Leuo-tli, 65-75 (83)/*; traii.sdiameter at widest part, 21-23 

 (25)m; dorsoveutral diameter in oblique girdle, 6-8 (8)/^; axes of nucleus, 5i^ 

 and 32a*. Dimensions of Schiitt 's figures (1895, pi. 23, figs. Tli-) are given in 

 parentheses. 



OcciTKEExCE. — This species was recorded in the plankton taken 4 to 11 miles 

 off La Jolla, California, in July and August, 1917, in hauls taken from depth 

 of 80 to 20 meters to the surface in surface temperatures of 18-8 C to 22-5 C. 

 It was not recorded in all the catches, but in considerably more than half of 

 them. As high as fifteen individuals were noted in one collection. It was never 

 noted in the plankton taken daily at four-hour intervals off the pier at the 

 Biological Station. 



It was also recorded July 3, 1906, in a haul 2.75 miles off La Jolla from 

 155 meters to the surface in a surface temperature of 20?4 C. 



Schiitt (1895) figures it presumably from the Bay of N'aples or from the 

 collections of the Plankton Expedition in the Atlantic. The records of Gipnno- 

 dinium teredo made by Schroder (1900) at Naples may exclude this species 

 since he cites only Pouchet's (1885a) figure, which is Torodininm teredo. On 

 the other hand Lebour (1917?>) notes a "variety of shapes" in the material of 

 G. teredo at PhTuouth. This suggests the occurrence of this species in her 

 material. 



AcTmxiES. — This is an exceeding active organism, darting aboiit in long 

 trajectories with little curvature. Its incessant rotation makes observation 

 difficult. When quiescent it usually lies -svith the left side uppermost and is 

 not easily dislodged, suggesting some adhesive function of the sulcus which on 

 the applied face may be locally active in taking hold on the substrate. The 

 antapical region is particidarly difficult to interpret owing in part it seems to 

 some mobility of the borders of the girdle and siilcus. 



CoMPARisoxs. — This species differs from T. teredo in its stouter body and 

 shorter main axis, 75/* as against 110^. The main distinction, however, appears 

 to lie in its possession of a reversed terminal anterior loop of 0.75 turn of the 

 sulcus. This is wholly lacking in T. teredo (fig. II, 4). The turn of the sulcus 

 immediately above the girdle is a trifle shorter (0.4) in T. rohustum than in 

 T. teredo (0.5). The more greenish tone noted in the plasma in our specimens 

 and in the so-called chromatophores as compared with the ochraceous tones of 

 Schiitt 's (1895) may be wholly a metabolic phenomenon and not a specific dis- 

 tinction. Our observations lead us to the conclusion that T. rohustum and T. 

 teredo are not phases due to contraction or metabolism of the same species. 



