222 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA 



A small sacklike pusiile is iisually present, opening into the anterior flagellar pore. The 

 cytoplasm is granular and generally shows numerous cell inclusions. These include minute 

 spheroidal oil droplets in the peripheral zone, a dense laj-er of sliort blue-green rodlets perpen- 

 dicular to the surface, large pinkish vacuoles and food bodies. This species showed more 

 remarkable cannibalistic habits than any other species of the Gymnodiniidae which we examined. 

 Many specimens were met in which the body had been greatly enlarged, sometimes t'n-ice the 

 normal size, by the ingestion of other unarmored dinoflagellates. These would often continue 

 active until the water on the slide had partly evaporated, wlien the food mass would be ejected 

 from the body by a posterior vent. The host would continue swimming about with the posterior 

 vent in the body gradually folding and closing in until it became invisible. One encysted 

 individual was noted which contained a large food mass, evidently the remains of a dinoflagellate. 



The surface is covered with longitudinal equidistant striae, about 18 across the ventral face 

 of the epicone. These are about twice as numerous on the hypocone as on the epicone. They 

 may be composed of unbroken lines from the apices to the girdle or may be short, broken lines 

 or granules linearly arranged, diminishing in number as they near the apices. Their color is 

 bhie green. Between the striae in surface view are seen the ends of the peripheral layer of 

 short rodlets. 



One individual when first observed was suffused at both poles (pi. 2, fig. 2-4) with a reddish 

 brown tone, fading out centrally. This color, however, soon faded out. leaving no trace and no 

 aggregated condensations of colored sub.stances. In general the color is a mixture of pale 

 chalcedony yellow and pinkish cinnamon diffused through the cytoplasm. Many individuals 

 enclosed in thin-waUed hyaline cysts were noted. 



Di:MEisrsioxs. — Length, 66-85/^1; transdiameter, 48-72^^; axes of nucleus, 22/^ 

 and 32^. 



OccrRREXCE. — This was figured by Dogiel (1906) from the Bay of Xaples, 

 ]May to July. The first appearance of this species in the Pacific was recorded 

 July 19, 1906, from a haul made with a No. 20 silk net from 585 meters to the 

 surface off La Jolla, California. During Jime. July, and August, 1917, this 

 was present in most of the hauls made off La Jolla, including a few of the 

 surface hauls at the end of the pier at the Biological Station. The number of 

 individuals noted in a short examination of a single haul varied from 1 to 10. 

 It was the most abundant species of the G}Tnnodinioidae in plankton examined 

 by us. 



CoMrABisoxs. — The food habits of this minute form make it one of the most 

 interesting species in the genus. In the many individuals seen practically none 

 was without ingested food masses. It is more sensitive to the adverse conditions 

 found under the microscope than most of the other species, in that the food 

 masses were usually disgorged shortly after being placed under observation. 

 This may have been caused by contact with the cover glass or by the intense 

 illumination required for the microscope. In its abundance of peripheral rod- 

 lets it resembles Gyrodinium fissiim and, less strikingly, Gymnodinium doma. 

 It belongs to the suljgenus Lineadinium and appears to be unique in the well 

 defined and seemingly general contrast in the number of striae on the epicone 

 and hypocone. A slight excess on the hypocone appears also in G. nib mm (fig. 

 Y, 4) and in G. midtistriatum (fig. Y, 1). 



