KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 287 



OccuRBENCE. — Tlie first individual was taken July 13, 1917, with a No. 25 

 silk net, in a haul 1.25 miles off La Jolla, California, from 50 meters to the 

 surface and in a surface temperature of 20?6 C. It was again observed iu a 

 \mn\ made July 23, G miles off La Jolla, from 80 meters to the surface and in 

 a surface temperature of 20°8 C. 



Comparisons. — This species in its lack of striae on the surface and arrange- 

 ment of girdle stands close to G. mitra (fig. EE, 5) and G. fusiforme (fig. 

 EE, 8) . It differs from them, however, in its proportions, overhang of girdle 

 and torsion of the body. In the latter respect it recalls G. spirals (fig. DD, 14), 

 without having the surface striae of that species. It is the only species in the 

 genus with its general color blue, the dull glaucous blue of G. submarinum 

 appearing almost green. It does not, however, approach the clear cornflower 

 blue of Gijmnodininm coeruleum. 



Gyrodinium britannia nom. sj). nov. 



Text figure DD, 13 

 Spirodinium spirale var. aciiUim, Lebour (19176). p. 194, fig. IQd. 



Diagnosis. — A large species with long, fusiform body, its length 3.29 trans- 

 diameters ; girdle a descending left spiral displaced 1.42 transdiameters ; sulcus 

 extending from apex to autapex ( ?) ; surface sparsely striate ; carmine-colored 

 pigment. Length, 145/^. Plymouth Sound, England, August. 



Description. — The body is long, slender fusiform, widest in the middle and tapering at both 

 apices, its length 3.29 transdiameters at the widest part. The hypocone exceeds the epicone in 

 length by about 0.26 of its own length. The epicone is .subconical, about 50°, with slightly convex 

 sides and blunt, subsymmetrical apex. It has a length on the left and right sides of the sulcus 

 of 0.17 and 0.59 respectively of the total length of the body. The hypocone is more slender 

 posteriorly than the epicone with a more pointed antapex. It is elongate conical posteriorly, 

 about 45°, with a length on the left and right sides of 0.79 and 0.38 respectively of the total 

 length of the body. 



The girdle joins the sulcus at a distance from the apex of 0.17 of the total length of the body. 

 It sweeps around the body in a descending left spiral course, displaced posteriorly 1.42 trans- 

 diameters. The furrow is wide, about 0.09 transdiameter, and deeply impressed. The sulcus is 

 not definitely marked off as such in Lebour 's (1917?)) figure, but evidently extends from near 

 the apex to or near the antapex. The flagi'lla and pores are also omitted from her figure. 



The nucleus is ellipsoidal and located near the central part of the body. It is filled with 

 short, moiiiliforni chromatin strands, which are parallel to the longitudinal plane of the body. 

 Its major and minor axes are 0.59 and 0.5 transdiameters in length respectively. The surface of 

 the body is covered with equidistant, longitudinal lines, figured as about 15 across the ventral 

 face. These lines are further marked off by granides of earmine-colored matter, strung along 

 their length like beads on a string. These are most numerous on the epicone, especially near the 

 apex, with a few scattering granules on the posterior half of the hypocone. 



Dimensions. — Length, 145/* ; transdiameter, 44/^ ; axes of nucleus, 25/* and 21/*. 

 OcciTRRENCE.— Figured by Lebour (1917/>) from Plymouth Sound, England, 

 in August. 



