320 jMEMOIRS of THE UNIVERSITY OF CALIFORNIA 



becoming deeper in the intereingular area and the antapical region. The anterior flagellar pore 

 is located at the anterior junction of the girdle and sulcus, the posterior pore about one width of 

 the girdle below the distal junction. 



The nucleus is an ellipsoidal body filled with coarse, moniliform subparallel chromatin strands 

 in the postcrocentral part of the body. Its major and minor axes are about 0.6i and 0.35 trans- 

 diameter in length respectively. 



The sacklike pusule at the anterior pore is connected by a long tubular canal with the pusule 

 at the posterior pore, the whole structure forming a complete channel between the two openings. 

 The e}i:oplasm is finely granular and diffusely amber yellow in color. In the peripheral zone 

 are numerous, short, slender blue-green rodlets or rhabdosomes arranged at right angles to the 

 surface. In a surface view these appear as minute blue-green circles. The surface is finely 

 striate with eciuidistant blue-green striae composed of linear series of short dashes, about 28 

 across the ventral face of the epicone. These are about twice as numerous ou the hypoeone as 

 on the epicone. 



DiMExsioxs. — Length. TCV ; trausdiameter, 39m ; axes of nucleus, 25m and 1-4m. 



OccT'RRExcE. — Tliis species -was first observed July 12, 1903, in a surface 

 haul off La Jolla, California. It was met again July 9 and 11, 1917. in hauls 

 4 miles off shore, from 80 meters to the siu'face and in a surface temperature 

 of 19?8 C. 



Other records of the occurrence of this species are as follows: Schiitt 

 (1895) figures it from the material of the Plankton Expedition, presiunably 

 from the Bay of Naples or the Atlantic, Schi-oder (1900) lists it from the Gulf 

 of Xaples. and Lebour (1917?>) records it from Pl^anouth Sound. England. 



Syxoxymy. — Originally figitred by Schiitt (1895. pi. 22. fig. TO) as Gym no- 

 di ni urn spirnle Bergh var. ohtusa and later transferred by Lemmermann (1899) 

 to Spirodmmni by reason of its spiral girdle. Dogiel (1906) describes a 

 Gymnodinium imder this name, specifying neither new species nor Schiitt as 

 authority. His form is not, however, that which Schiitt (1895) has figured. 

 It is lai'ger, has greater contrast in the intervals between the ribs in the epicone 

 and hypoeone, a straighter longitudinal fiu'row, and very little displacement of 

 the distal end of the girdle below the proximal. This is 0.42 of the total length 

 in Schiitt 's figure and only 0.05 in Dogiel 's. The latter must therefore belong 

 in Gyuniodiuiuui. It appears to be identical with our Gymnodinium hetero- 

 striatum. 



CoMPAEisoxs. — A peripheral zone of short rodlets is not uncommon in both 

 Gyrodinium and Gymuodininm and is probably related to the metabolism of 

 the cell. These are most marked in Gyrodinium fission (fig. DD, 8) and G. 

 jjostniaculatiim (fig. DD, 20). The long radial rodlets are also repeated in 

 Gymnodinium pseud onoctiluca, G. dogieJi (pi. 3, fig. 34), G. pacliydermatum 

 (pi. 3, fig. 32). and G. amphora (pi. 3, fig. 26). These are not present in all 

 individuals of the species and are probably related to certain stages of 

 metal)olism. 



This species is close to G. fissum (Levander) (fig. DD. 8). but is yellow 

 instead of green, has much greater displacement of girdle, and broken lines in 

 its striae instead of continuous ones. 



