326 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA 



Gyrodinium pepo (Scliiitt) 



Text figure DD, 2 



Gymnoclinium spirale var. pepo Schiitt (ISQo), p. 112, pi. 21. figs. 69j_3. 

 Spirodinium spirale var. pepo. Leuimermann (1899), p. 359. 



"DiAGXosis. — A medium sized species ^Yith ovoidal flask-shaped body with 

 contracted eurved apex, its length 1.6 transdiameters ; girdle a descending left 

 spiral, displaced 0.5-t transdiameter ; sulcus extending from apex to antapex, 

 surface coarsely striate. Length, 81m. Atlantic ( ?) or Bay of Naples. 



Description. — The body is stout ovoidal. widest posteriorly and tapering anteriorly, its 

 length 1.6 transdiameters at the widest part, which is in the middle of the hypocone. The 

 epieone is slightly longer than the hypocone, but is much narrower. It has a length on the left 

 and right sides of 0.39 and 0.7 respectively of the total length of the body. The epicene contracts 

 towards the apex which is deflected towards the left side of the body with the left side of the 

 epieone concave and the right side convex. The hypocone is hemispherical behind the girdle 

 region with broad, smoothly contoured antapex. 



The proximal junction of the girdle and sulcus occurs at 0.39 of the total length of the body 

 from the apex. It sweeps around the body in a descending left spiral course and joins the sulcus 

 distally about 0.7 of the total length of the body from the apex, having a displacement of 0.54 

 transdiameter. The furrow is wide, O.OS transdiameter, and deeply impressed with smooth 

 borders. The sulcus begins near the apex and extends posteriorh' to within a short distance of 

 the antapex. The transverse flageUum arises at the anterior junction of the girdle and sulcus 

 and travei'ses the entire length of the girdle. The longitudinal flagellum arises slightly below 

 the posterior junction of the sulcus and girdle. 



The nucleus is broadly ellipsoidal, and is located in the anterior part of the body. Its major 

 and minor axes are about 1.56 and 0.40 transdiameters respectively. Coarse chromatin strands 

 fill the body of the nucleus. A large pusule is found in the posterior part of the hypocone, but 

 its connection with the posterior flagellar pore is not indicated. The c\i;oplasm is filled with 

 large vacuoles, closely crowded together. In the peripheral layer are minute spherules, longi- 

 tudinal, equidistant and about equal in number on both epieone and hypocone, about 24 across 

 the ventral face. Color? 



DiMExsioxs. — Length, 81^^; transdiameter, 50/^; axes of nucleus, 28^^ and 20/^. 



OccuERExcE. — Figured by Schiitt from the collections of the Plankton 

 Expedition from the Atlantic or the Bay of Naples. A single specimen "was 

 taken, 1.25 miles off La Jolla, California, July 25, 1906, with a Xo. 20 net, in a 

 surface haul. 



Syxontmt. — This species was figured by Scliiitt as Gymnodinium spirale 

 var. pepo. and later changed by Lemmermann (1899) to Spirodinium spirale 

 var. pepo. It has none of the characteristics of spirale, however, lacking the 

 slender fusiform shape of body, the wider displacement of the girdle, and the 

 slight torsion of the sulcus and body of that species. It cannot thus be consid- 

 ered a variety of that species and we therefore propose for it species rank, as 

 G. ]iepo. 



CoMPAEisoxs. — This species has the most rotund inflated hypocone found in 

 the genus. This feature, together with the curved apex, differentiates the 



