454 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA 



anterior loop makes nearly 0.75 turn, the intercingular region has about the same amount of 

 torsion, and the posterior loop somewhat more than 0.5 turn, a total torsion of approximately 

 2.25 turns. Uncertainty attaches to the distal limit of the sulcus anteriorly and to the exact 

 location of the flagellar pores. 



The ocellus is of the concentrated or integi-ated type. It is located at the anterior angle of 

 the hypocone, 0.33 of the total length from the anterior end at the left of the sulcus and just 

 posterior to the girdle. Its length is 0.25 transdiameter. Its axis appears to be parallel to the 

 major axis of the body and is directed anteriorly. It consists of an elongated subhemispherieal 

 lens whose exposed length equals its diameter and a ragged disk of pigment (reddish brown on 

 the plate), the diameter of which is twice that of the lens and 0.25 transdiameter of the body. 

 The color of the pigment of the individual figured is not stated in the pertinent text. 



The nucleus was so transparent as to have eluded observation. There is a large clavate 

 pusule near the ocellus, evidently attached to the anterior flagellar pore. The cytoplasm is 

 stated to have been transparent, colorless, and coarsely vacuolated. A red pigment fleck lies on 

 the anterior margin of the anterior loop of the sulcus. Free and encysted forms were seen. 



DiMEXSiojTS. — Length, 104a'; transdiameter, 47^^; length of ocellus, 12/*. 



OcciTRRENCE. — Figured from the Atlantic at Concarneaii, France, by Poiichet 

 (1885&) and stated by him later (1892, 1894, p. 170) to occur in typical form 

 in the plankton of Dyref jord, Iceland, in July and August, at 10° C. 



Comparisons. — This species is the only one in Pouclietia with an ocellus so 

 far anterior except P. compacta Schiitt, and there is some doubt about the 

 orientation of that species. P. fusus Schiitt and P. maxima sp. nov. have a 

 premedian ocellus, but not so far anterior as in P. polyphemtis. The l)ifid 

 antapex, the character of the anterior and posterior loops of the sulcus, and 

 the orientation of the ocellus combine to confirm the correctness of the orien- 

 tation which we have given to Pouchet's figure. This species is not far from 

 P. juno and P. violescens in girdle, sulcus, size, form, and structure and location 

 of the ocellus. The differences between them appear to lie in the color and 

 surface differentiations and in the direction of the axis of the ocellus. P. 

 poltjplicmvs is colorless and has neither longitudinal markings nor platysomes; 

 the axis of its ocellus is longitudinal, while in the two species named this axis 

 is horizontal. P. violsecens is colored and has longitudinal markings and P. 

 juno has peculiar platysomes. Ponchetia polyphemus belongs in the subgenits 

 PonchetieTla. 



Synonymy. — This species was originally described by Pouchet (1884, 

 1885a, t), apparently from a complex of forms which he did not clearly analyze, 

 and within which he noted (1885fl) a considerable range in size, color, and 

 structure, which he imperfectly interpreted, and an inconstancy of occurrence 

 of the ocellus. These facts, with our present knowledge of the group, afford 

 conclusive proof that he confused species of Ponchetia with those of other 

 genera, and establish also the probability of confusion of species within the 

 genus of Ponchetia itself. 



His statement (1886) that the ocellus develops by the fusion of the refringe- 

 ent spherules into one body and the retraction of the pigment into one cap- 

 shaped mass seems rather to be a hypothetical interpretation based on different 



