KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 303 



Dimensions. — Length, 50m; transdiameter, 26/*; axes of nucleus, 36/* and %. 



OccTTRBExcE. — A single individual was taken August 15, 1917, ^Yi.th a No. 25 

 silk net, 0.75 mile off La Jolla, California, in a haul from 80 meters to the surface 

 and in a surface temperature of 21 ?9 C. 



Comparisons. — This species, in the torsion of the girdle, foreshadows the 

 Cochlodinium t^rpe of furrow arrangement. The overhang, however, is still 

 considcra])ly less than in that genus. Tliere is no non-striate species of 

 Gi/rodinitDit which approaches it in proportions. 



Gyrodinium flavidum sp. nov. 



Plate 7, figure 73 ; text figure CC, 20 



Diagnosis. — A large species with asymmetrical, rotund ellipsoidal body, its 

 length 1.5 transdiameters ; girdle a descending left spiral, displaced 0.54 trans- 

 diameter ; sulcus extends from apex to antapex ; color, oehraceous grey. Length, 

 102/*. Pacific off La Jolla, California, August. 



Description. — The body is robust ellipsoidal, asymmetrical with the ventral face more convex 

 than the dorsal face, its length 1.5 transdiameters at the widest part. A cross-section of the 

 body is nearly circular in outline. The hypocone exceeds the epicoue in size, its length being 

 greater by 0.25 of its own length. The epicone is asymmetrical, the left side being raised in a 

 high shoulder effect, throwing the apex, a knoblike extension, somewhat to the right. It has a 

 length on the left and right sides of 0.16 and 0.51 respectively of the total length of the body. 

 The hypocone is also asymmetrical, but less so than the epicone. Its sides are rounded and the 

 antapex forms a short knoblike projection. It has a length on the left and right sides of 0.76 

 and 0.41 respectively of the total length of the body. The parts of both epicoue and hypocone 

 bordering the girdle are drawn out into wide, shelflike ridges. 



The girdle is premedian in position for most of its course. Its proximal end joins the sulcus 

 at a distance from the apex of 0.16 of the total length of the body. It sweeps around the body 

 in a descending left spiral course to meet the sulcus at a distance from the apex of 0.51 of the 

 total length of the body. The furrow has a width of about 0.07 transdiameter, and is deeply 

 impressed, with borders raised somewhat above the surrounding surface of the body. The sulcus 

 is a narrow trough extending in a slightly sinuous line from near the apex to near the antapex. 

 The anterior flagellar pore opens at the anterior junction of the girdle and sulcus, the posterior 

 pore midway between the distal junction and the antapex. 



The nucleus is a spheroidal body found in the left side, slightly anterior to the equatorial 

 plane. It is filled with moniliforin, chromatin strands spirally arranged. Its axis is about 0.;15 

 transdiameter in length. 



The cytoplasm is coarsely granular, especially near the surface, giving the organism a mottled 

 appearance. It was filled with large vacuoles of the same color as the surrounding cytoplasm, a 

 pearl grey. Scattered throughout the cytoplasm but becoming much denser at the apices are 

 minute granules of oehraceous orange and near the surface green oil droplets. Nutrition is 

 evidently holozoic, as the cytoplasmic inclusions are probably the products of metabolism. A 

 small sacklike pusule opens into the posterior flagellar pore. In other individuals one was 

 present at the anterior pore also. No striae were detected on tlie surface. 



