340 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA 



Dimensions. — Length, 79-90^; transdiameter, 52-68/^; axes of nucleus, 84/^ 

 and 48^*. 



OccuRREXCE. — Two individuals were taken August 8, 1917, with a Xo. 25 

 net, 4 miles off La JoUa, California, in a haul from 80 meters to the surface 

 and in a surface temperature of 21-9 C. 



AcxmTiES. — The movements of this organism were rather sluggish, showing 

 a slow clockwise rotation. It invariably came to rest with the ventral face on 

 the substrate. 



CojNIPArisons. — The relative propoi'tions and size of this species alone 

 separate it from G. corallinum (fig. DD, 12) . The type of nucleus is peculiar 

 and constant in all of the individuals of both species that were observed. A 

 similar structure is found in Gijmnodinium rutrum (pi. 8, fig. 86). It is unlike 

 anything found elsewhere in the CxAnnnodinioidae. 



One might be inclined to regard this sx)ecies as an aberrant form of G. 

 corallinum were it not for the fact that several individuals referable' to it, of 

 apparently normal status, have been encountered. In addition the relative 

 deg]'ee of displacement of the girdle, with reference to the transdiameter, sep- 

 arates it from that species, as does also the location of the posterior pore. The 

 marked differences in the shape of the nuclei in the two species may l^e due to 

 approaching mitosis in the individual of G. virgation which we figure, and not 

 to a fundamental specific difference. 



Gyrodinium viridescens sp. nov. 



Plate 4, figure 48; text figure DD, 11 



Diagnosis. — A small species with broadly subfusiform body, concave pos- 

 teroventrally, dorsoventrally flattened, its length 1.95 transdiameters ; girdle 

 disj)laced one transdiameter ; sulcus encircling an apical lobe and reaching the 

 antapex; surface striate; color, pale pea green; littoral habitat. Length, 45m. 

 Sandy beach of the Pacific at La Jolla, California, July. 



Description. — The body is broadly subfusiform, asjoninetrical, taperiug anteriorly, obliquely 

 truncate posteriorly, its length 1.95 transdiameters. Its greatest transdiameter is near the middle 

 of the hypocone, slightly anterior to the middle of the body. The dorsoventral diameter is 0.66 

 of the transverse one. The epicone forms less thau 0.3 of the total body, its altitude at the 

 proximal and distal ends of the girdle being respectively 0.13 and 0.61 of the total length of 

 the body. Owing to the rapid descent of the distal end of the girdle the right ventral lobe of 

 the epicone is projected posteriorly as a slender triangular process. The apex is a rounded cone 

 higher than a hemisphere and somewhat more rotund on the left face and bears a central lobe 

 or button about 0.2 transdiameter across, encircled by the anterior end of the sulcus. The 

 hypocone forms more than 0.7 of the whole body, and is higher and more convex on the left than 

 on the right side. From the midventral level posteriorly tlie whole ventral face is flattened and 

 somewhat concave centrally, to such an extent that the posterior margin lies dorsal to the major 

 axis. The antapex is obliquely truncate for a width of 0.5 transdiameter and slopes from the 

 left posteriorly to the right at an angle of 10° from the horizontal. 



