KOFOID AND SWEZY: UNARMORED DINOPLAGELLATA 181 



of the body a distinctly wavy appearance (fig. Z, 7). This layer is about Iju in thickness. On 

 the surface of the body are striae of l)roken lines, linearly arranged and spaced at about 3/i 

 near the girdle, twenty-three across the ventral face. 



DiiMENSloxs. — Length, 97-115/^; trausdiameter, 50-75/^; axes of niicleiis, 

 25-36/^ and 22-28;^. 



OccrRRF.xcE. — The individual figured was taken Jttly 9, 1917, 4 miles off 

 La Jolla, California, with a No. 25 silk net in a haul from 80 meters to the 

 surface and in a surface temperature of 19-2 C. On July 11 another individual 

 was observed in a surface haul made at the same place, with the same apparattis. 

 It was seen again on August 13, 0.75 mile off La Jolla in a haul from 83 meters 

 to the surface. 



CoMPARisoxs. — Lebour (1917&) descrilies a form to which she gives the 

 name G. achromoticuni, which is somewhat similar to our species, and yet 

 presents striking differences. The general shape and proportions differ only 

 in a slight degree (fig. Y, 8). The most striking difference is in the lack of a 

 differentiated ectoplasm in G. achrontaficnm, which in G. ahhreviatum gives 

 the characteristic appearance to the surface. This species shows the same 

 differentiated ectoplasm found in G. dogieli sp. nov., G. pacliydermatum sp. nov., 

 and G. amphora sp. nov. (figs. AA, 1, 5, 6), and, like them, it belongs to the 

 subgenus PacJiijdiitiuui. In its color it stands alone in Gijmnodinium, and in 

 displacement of girdle exceeds that in the species above named. 



Gymnodinium achromaticum Lebour 



Text figure Y, 8 

 Gi/mnodinium achromaticum Lebour (1917&), p. 190, fig. 5. 



Diagnosis. — A medium sized species with ellipsoidal Iwdy, its length 1.62 

 transdiameters ; girdle premedian, dis]:)laced aljout twice its own width ; sulcus 

 extending from girdle to antapex ; surface coarsely striate ; colorless. Length, 

 78/^. Phinouth Sound, England, July. 



Description. — The body is a.syinmetrically and broadly ellipsoidal in ventral view, with 

 broadly rounded apices, ovoidal in lateral view, narrowing posteriorly, its length 1.62 trans- 

 diameters at the widest part. The narrowing of the dorsoventral diameter occurs only in the 

 posterior jiart of the hypoeone. The epicone is much smaller than the hypocone, being exceeded 

 in length by 0.24 of the length of the hypocone. Its shape is that of a broad, flat cone, about 

 90° in lateral view, 120° in ventral view, with blunt apex excentrieally placed sinistro-ventrad. 

 Tt has a length on the left and right sides of about 0.29 and 0.48 respectively of the total length 

 of the body. The hypocone is long with subparallcl sides in ventral view, tapering posteriorly 

 in lateral view. The antapex is broad and truncate, marked ventrad by the sulcal notch. 



The girdle is premedian, joining the proximal end of the sulcus at a distance from the apex 

 of about 0.29 of the total length of the body. It sweeps around the body in a descending left 

 spiral course, its distal end joining the sulcus 0.48 of the total length of the body from the apex, 

 and is disjilaeed about twice its own width. The furrow is wide, about 0.08 trausdiameter, and 

 is deeply impressed, with overhanging sides. The sulcus apparently extends upon the epicone 

 for a short distance and posteriorly to the antapex in a slightly sinuous line. The flagella and 

 pores are not figured by Lebour (19176). 



