KOFOID AND SWEZY: UNARMORED DINOPLAGELLATA 335 



Description. — The body is irregular, asymmetrical obovoidal in outline, its broadest traus- 

 diameter premedian, its length 1.8 traiisdiameter at the widest part, which is at the girdle. The 

 entire outline of the body is uneven and ridged, but without wrinkling of the pellicle resulting 

 from shrinkage. The size of the hypocoue is somewhat greater than that of the epicone, its 

 length being greater by 0.13 of its own length. The shape of the epicone is roughly conical 

 (50°) with irregular metabolic sides. It has a length on the left and right sides of 0.32 and 0.56 

 respectively of the total length of the body. The apes is blunt and notched by the sulcus. The 

 hypoeone is somewhat narrower (35°) than the epicone, also irregular in outline, with a more 

 slender, pointed antapex. Its length on the left and right sides is about 0.65 and 0.43 respectively 

 of the total length of the body. 



The girdle is premedian for the greater jiart of its lengtli. Its proximal end joins the sulcus 

 at a distance from the apex of 0.32 and its distal end 0.56 of the total length of the body. The 

 first 0.5 transdiameter of its course follows a nearly transverse direction around the body, beyond 

 which it is deflected posteriorly in an increasingly steeper angle, its distal end being displaced 

 about 0.43 transdiameter. The furrow is narrow, its width being about 0.03 transdiameter, and 

 is deeply impressed with overhanging borders. 



The sulcus extends from the apex to the antapex as a shallow, narrow trough. Its direction 

 is that of a sigmoid curve anteriorly, less sinuous posteriorly. The anterior flagellar pore opens 

 at the proximal junction of the girdle and sulcus, the posterior pore midway between the distal 

 junction and the antapex. 



The nucleus is spheroidal and situated in the right central part of the bo<ly. It is filled with 

 coarse chromatin strands. Its axis is about 0.3 transdiameter in length. 



A small sacklike pusule opens into each flagellar pore. The cytoplasm presented a foamy 

 appearance with finely granular constituency and was completely filled with large vacuoles 

 containing a pink fluid, with blue-green droplets and dark, refractive granules. These were so 

 massed together as to give the body a den.se appearance and without sharp contrast in its various 

 parts. The basal color of the cytopla.sm is pearl grey with minute dots of yellow ochre which 

 become dense in the girdle region, the anterior part of the sulcus and at the antapex. A thick 

 cluster of melanin granules was present in the apical region on the right side of the sulcus. 

 There were no striations or other .surface markings. 



Dimensions. — Length, 146?^ ; transdiameter, 81/^ ; axis of nucleus, 26/^. 



Occurrence. — A single individual was taken August 21, 1917, with a No. 25 

 silk net, 5 miles off La Jolla, California, in a haul from 83 meters to the surface. 



Co:\rrARisoxs. — In the foamlike structure of its cytoplasm, which may, how- 

 ever, be only a transient meta])olic condition, this species resembles G. favidum 

 (pi. 7, fig. 73) and Gymnodinium midtistriatum (pi. 4, fig. 37), ^\ithout the firm 

 pellicle of the latter species. It is the only species in the genus showing the 

 presence of melanin which is common in the more highly specialized genera, 

 Ponchetia and Enjthropsis. This may have come from ingested food. Its 

 labile body is unique in Gyrodinium. 



Gyrodinium submarinum sp. nov. 



Plate 10, figure 110; text figure DD, 1 



Diagnosis. — A large species with slender fusiform body, its lengtli 3.54 

 transdiameters ; girdle a descending left spiral, disi)laced 1.75 transdiameters ; 

 sulcus extending from apex to antapex; surface striate; color, dull glaucous 

 blue. Length, 117/^. Pacific off La Jolla. ralifornia, July. 



