288 MEMOIKS OF THE UNIVERSITY OF CALIFORNIA 



Syxoxtmt. — This form was described by Lebour (1917&) as Spirodininm 

 spirale var. acutum Scliiitt. It differs from Sdiiitt's figure (1895), howeTer, 

 in its proportions and more strikingly in its coloring, and also in its c}i:oplasmic 

 structure. Surface striae are apparently lacking in Schiitt's species. These 

 differences seem to be too great to allow it to remain with Gyrodinium ncutum, 

 hence we propose for it specific rank with the name G. britannia. 



CoMPAEisoxs. — In the possession of red pigment this species stands near 

 G. coralUuHin (pi. 10, fig. 117) and G. virgatnm (pi. 10, fig. 112), differing from 

 them, however, in other impoi-tant respects, such as proportions and shape of 

 body and type of nucleus (see figs. DD, 12, 13, 21) . 



Gyrodinium capsulatum sp. nov. 



Plate 5, figure 54; text figure CC, 14 



DiAGxosis. — This is a small species with broadly ovoidal liody. its length 

 1.26 transdiameters ; girdle submedian, a descending left spiral displaced 0.38 

 transdiameter ; sulcus short on epicone, extending to antapex; color, orange 

 green. Length, 45/*. Pacific off La Jolla, California, July, August. 



Descriptiox. — The body is broadly ovoidal, with broad, rounded apices, widest posteriorly, 

 its length 1.26 transdiameters at the widest part. The epicone exceeds the hj-poeone in length 

 by about 0.2 of the total length, but not in volume, as its transdiameter is narrower. The epicone 

 is smoothly rounded with broad apex. It has a length on the left and right sides of 0.4 and 0.69 

 respectively of the total length of the body. The hypocone is hemispherical in shape, somewhat 

 mder than the epicone, with smoothly rounded or slightly notched antapex. 



The girdle is submedian in position, its proximal end joining the sulcus at a distance from 

 the apex of 0.4 and its distal end 0.69 of the total length of the body. It follows a descending 

 left spiral course around the body, its distal end displaced about 0.38 transdiameter. The furrow 

 is wide, about 0.08 transdiameter in width, and is deeply impressed with smooth, overhanging 

 borders. The sulcus invades the epicone for a short distance, narrowing rapidly from a wide 

 trough at the girdle to a slender line. Posterior to the anterior flagellar pore the overhanging 

 borders of the sulcus nearly obliterate the furrow, immediately spreading out again to form a 

 wide, deep trough which reaches to the antapex. Its borders are mobile, overhanging, giving a 

 slightly sinuous line to the course of the sulcus. The anterior flagellar pore is found about 0.5 

 of the width of the girdle posterior to the proximal junction of the girdle and sulcus, and the 

 posterior pore is slightly behind their distal junction. 



The nucleus is a large, ellipsoidal body situated immediately below the equatorial plane, with 

 its major axis slightly oblique to the short axis of the body. It is filled with fine, moniliform 

 chromatin strands following the course of its major axis. Its major and minor axes are about 

 0.73 and 0.44 transdiameter in length respectively. 



In the individual figured pusules were not evident. In another specimen a single long, tube- 

 like pusule opened into both the anterior and po-sterior pores. The c}i:oplasm is finely granular 

 and transparent. Scattered through it are greenish yellow patches of irregular shape and a 

 few oil droplets of the same color. Near the periphery are numerous club-shaped vacuoles filled 

 with the pink fluid such as is found in the pusules. These appear to be in the process of opening 

 to the exterior. The color is pale green yellow distributed throughout the cytoplasm. Beneath 

 the pellicle is a layer of orange color which forms a border around the body in optical section. 

 A clearly marked, double-contoured periplast fonns the periphery of the body. Around the 

 body and closely following its contour is a hyaline thin-walled cyst. A second cyst is formed 

 around this, miich larger than the first and closely following its outline. 



