KOPOID AND SWEZY: UNAKMORED DINOFLAGELLATA 209 



the left side can be ti-aeed into the epieone M'here the suhuis is absent as a distinct furrow. The 

 anterior flagellar pore is found near the lower border of the proximal end of the girdle and 

 sulcus. The transverse flagellum usually traverses the entire length of the girdle. The posterior 

 pore is slightly posterior to the distal junction of the girdle and sulcus. 



The nucleus is spheroidal, and situated below tlie girdle on the left side of the hypocone. Its 

 axis is about 0.3 transdiameter. 



The cytoplasm is clear and pearl grey in color. In the peripheral zones are leaflike chromato- 

 phores of strontium yellow color. These are quite variable in size and also in number, ranging 

 from 2 to 20 or more. In the deeper parts of the protoplasm are numerous blue-green bodies, 

 usually one large one in the posterior half of the body and much smaller ones located elsewhere. 

 In the peripheral zone outside the layer of chromatophores are numerous, minute yellowish 

 green rodlets, invisible under the low powers of the microscope. Tliese may vary from a denselj^ 

 packed layer to a few scattered ones and are probabh- metabolic in origin. No striae or other 

 surface markings were detected. 



Dimensions. — Length, 26-35/^; transdiameter, 21-28m; diameter of nucleus, 

 10m. 



Occurrence.^ — This species was present in very great abundance during an 

 outbreak of yellow water, Jidy 27 to August 1.3, 1914, along tlie shore at La 

 Jolla, California. No other organisms were present in any considerable 

 num})ers. In some siu'face hauls it was present almost to the exclusion of all 

 other organisms, and in all the hauls made near the Biological Station at that 

 season it Avas by far the most abundant form. It entirely disappeared from 

 the hauls shortly after the cessation of the yellow Avater. A single indiAddual 

 was taken Jid}^ 8, 1917, 4 miles off La Jolla, in a haul from 80 meters to the 

 surface and in a surface temperature of 19-8 C. 



Phosphorescence. — Diuing the occurrence of the yellow water above re- 

 corded there was a great display of phosphorescence in the breakers along the 

 shore. A fcAv Gonyaulax and Noctiluca Avere present in the hauls made, but in 

 numbers far too small to account for this display. Unfortunately no laboratory 

 tests Avere made to determine the Imninescence of Gi/nmodinium pavum. It 

 Avas, howeA'er, the only organism present in sufficient numbers to justify the 

 claim made for it, i.e., that it is strongly hmiinscent. 



Comparisons. — This species most nearly resembles the related arenaciphilous 

 form, G. agile, from beach sands at La Jolla, but differs from it in the relatiA'e 

 proportions of epieone and hypocone, in a smaller compression of the body and 

 in the color of its chromatophores. It belongs to the subgenus Gyninodinium. 



Gymnodinium fulgens noui. sp. uoa'. 



Text figure X, 30 

 Gymnodinium psrudoiwctiluca Lebour (1917b), p. 188, fig. 3. 



Di.\GN0sis. — A large species Avith stout, fusiform body, its length 2.27 

 transdiameters ; girdle Avithout displacement; sulcus extending from girdle to 

 antapex; yelloAA' chromatophores. Length, lOOi". Plymouth Sound, England, 

 June, July. 



