KOFOID AND SWEZY: UNARMORED DINOPLAGELLATA 289 



Dimensions. — Length, 45-50/^; transdiameter, 33-40/^; major and minor axes 

 of nucleus, 25;^ and 2Sp- ; leng-fh of outer cyst, 62/^. 



Occurrence. — The individual figured was taken July 2, 1917, 6 miles off 

 La Jolla, California, with a No. 25 silk net, in a haul from 60 meters to the 

 surface and in a surface temperature of 21?9 C. It was noted again on August 

 6, in a surface haul 4 miles offshore and in a surface temperature of 21 ?2 C. 



Comparisons. — This species stands nearest to Gij)nnodininin in its type of 

 girdle arrangement, having somewhat less displacement than other species of 

 the genus. The orange color in its peripheral layer recalls the same color and 

 location in Gymnodinimti dogieli (pi. 3, fig. 34) and G. pachydermatum (pi. 3, 

 fig. 32), without, however, being correlated with the characteristic ectoplasmic 

 diffei-entiation of those species. 



Gyrodinium caudatum sp. nov. 



Plate 9, figure 102 ; text figure CO, 1 



Diagnosis. — Body broadly fusiform, its length 1.94 transdiameters, Avith 

 apical and antapical processes subequal, very stout, the ajncal truncate ; girdle 

 displaced about 0.5 transdiameter, with slight overhang; color, primuline 

 yellow; length, 66/*. Pacific off La Jolla, California, July. 



Description. — The body is broadly fusiform with abruptly eoutracted apical and antapical 

 processes, its length 1.94 transdiameters; dorsoventral and transdiameters equal. Epicone and 

 hypocone are about equal. The epicone has a length on the left and right sides of 0.27 and 0..59 

 transdiameters respectively. It is subhemispherical above the proximal end of the girdle and 

 contracts to a stout apical process in the form of a truncate cone 0.27 transdiameter in length, 

 its basal diameter equaling its altitude, and stout, slightly truncate apex having a diameter of 

 0.66 of its base. It is slightly deflected dorsally. The hypocone is similar in size and general 

 form to the epicone, tapers a trifle more gradually into the antapical process, which in our 

 specimen is conical, with a length of ai)proximately 0.4 transdiameter and a basal diameter of 

 0.66 its length. It is deflected ventrally for about 10° from the axis. The antapex is broadly 

 rounded. 



The girdle forms a descending left spiral displaced distally about 0.25 the total length of the 

 body, with slight overhang. The furi-ow is rounded, deeply impressed in its proximal part, less 

 so distally, and has no protuberant or overhanging lips. The anterior flagellar pore is at the 

 upper angle of the proximal end, and tlie fiagellum traverses about 0.5 of the circumference. 

 The sulcus could be traced for a short distance as a narrowing groove anterior to the girdle. It 

 passes posteriorly with a sigmoid flexure to about an equal distance beyond its junction with the 

 distal end of the girdle. The posterior flagellar pore lies midway between the two ends of tlie 

 girdle. 



No surface markings could be found on the pellicle. Tlie nucleus lies near the center of the 

 midbody to the right and below the proximal end of the girdle. It contains numerous beaded 

 chromatin threads polarized to the left and anteriorly. It seems to be crowded to one side by 

 the large, opaque, dull greenish yellow mass enclosed in a vacuole, probably a food ball. Adjacent 

 to this are several highly refractive oil globules. A small sacklike pusule with pinkish contents 

 forms a diverticulum directed posteriorly from the anterior flagellar pore. A sulphine-yellovv 

 sphere is found in the posterior part of the hypocone. 



