254 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA 



proximal junction with the girdle, narrows somewhat at the distal junction and expands and 

 deepens near the posterior part of the hody. The anterior flagellar pore is found at the proximal 

 junction of the girdle and sulcus and the posterior pore aboiit 0.18 transdiameter below the 

 distal junction. 



The nucleus is ellipsoidal and is found near the proximal end of the girdle on the left side 

 of the body. It is composed of two distinct regions : an inner region which is granular or may 

 exhibit moniliform chromatin strands, and surrounding this a zone which exhibits no differ- 

 entiating structure. This zone has a width of about 0.17 transdiameter and has a double- 

 contoured outer membrane. In one case it seemed to have the vacuolate structure similar to 

 that found in the nucleus of Gyrodinium, corallinium (pi. 10, fig. 117). The major and minor 

 axes of the nucleus are 0.4 and 0.3 transdiameters in length respectively. 



A saeklike pusule is usually present at the anterior flagellar pore. In some individuals it 

 was present at both pores. The cytoplasm is remarkably clear and transparent. Among all 

 the specimens observed very few possessed cell inclusions, such as food masses and oil globules. 

 Many were seen, however, with what appeared to be a food vent at the posterior end of the body, 

 as if a large food mass had been recently ejected. The color of the cytoplasm is pale diffused 

 rose red at the anterior end, shading posteriorly to pale sea-foam yellow or pale glaucous green. 

 These colors are strongest at the apices and appear to be diffused througli tlie cytoplasm. 

 Minute granules of rose red pigment are usually present in the periphery of the hody, strung 

 along the surface striae like beads on a string. These are most numerous at the apex and girdle, 

 the largest granules being found along the proximal border of the girdle. On the hypocone 

 they are scattering, few in number, and widely separated. 



The surface is striate, with longitudinal, equidistant lines. The number of lines on the 

 epieoue is about half that on the hypocone. They are clear greenLsh yellow, and may be 

 continuous or may be composed of sliort, broken dashes. 



DiMEXsioxs. — Length, 100-145^'; transdiameter, To-90m; axes of mtcleus, 

 35-37M and 25-27/«. 



OccuERExcE. — This species was foiuid ahnndantly in most of the liauls made 

 between July 11 and August 22, 1917, and was present in surface hauls as well 

 as those made from 80 meters to the surface, and at distances offshore varying 

 from the end of the pier at the Biological Station at La JoUa, California, to 

 10 miles. 



CoMPARisoxs. — This species is unique in the genus Gijmuodiuium in pos- 

 sessing a nucleus composed of two distinct parts. This was found in all the 

 individuals observed and thus could not be a temporary condition characteristic 

 of some particular stage in the life history. Dividing forms, however, were 

 notably absent in all the material under observation. The same tA'iie of nucleus 

 is present in Gi/rodhiiinn coraUiinim and G. virgatnm. Here, again, the ap- 

 pearance of the dividing nucleus was not observed. 



It belongs to the subgenus Lineadiniu)ii, Init the degree of displacement of 

 the girdle and torsion of the body bring it close to the genus Gyrodinium. The 

 similarity of its nucleus to that of certain species in that genus strengthen the 

 relationships. It is on the border line between the genera Gymnodinium and 

 Gyrodinium, and might be included in either without violence to its structural 

 revelations. 



It is near Gymnodimum line(dum sp. nov. (fig. Y, 14), but differs in its 

 surface markings, form of hypotheea, and lability. 



