258 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA 



Dimensions. — Length, 66/^; transdiameter, 55/*; axes of niideiis, 19/^ and 15/*. 



OccFRRENCR. — One individual was taken Jnlv 26, 1917, with a No. 25 silk 

 net, 2.5 miles o& La Jolla, California, in a haul from 80 meters to the surface 

 and in a surface temperature of 21?6 C. Another was taken August 17, with 

 the same apparatus and from the same depth, 0.75 mile off La Jolla, and on 

 August 21, in a haul 5 miles offshore and from 83 meters to the surface. 



Comparisons. — This species belongs in the subgenus Paclujdiniiun along 

 with G. dogicli sp. nov., G. amphora sp. nov. (figs. AA, 6, 8), and other species 

 characterized by a thickened periplast. There is less structural differentiation 

 in that region in this species than in the remainder of the group. The slight 

 undulations of the surface, particularly noticeable along the borders of the 

 girdle, leave little doubt about the character of the layer of protoplasm inune- 

 diately beneath, hence its inclusion with that subgenus. In the richness of its 

 coloring and the cytoplasmic inclusions it resembles the larger species of that 

 subgenus, notably G. amphora and G. dogicli, being unlike them, howe^-or, in 

 havins surface striae. 



Gymnodinium sphaericum Calkins 



Plate 4, figure 42 : text figure AA, 9 

 Gymnodinium gracilc var. sphacrica Calkins (1902), p. 429, fig. 20. 



Diagnosis. — This is a medium sized species with rottuid. spheroidal body, 

 very slightly flattened dorsoventrally, its length and transdiameter nearly equal 

 or the length may be about 1.27 transdiameters ; girdle premedian, displaced its 

 own width or slightly more ; sulcus short on the epicone, extending to antapex ; 

 color, amber yellow and olive ochre. Length, 60/*. Atlantic off Woods Hole, 

 Massachusetts, and Pacific off La Jolla, California, July, August. 



Description. — This is a medium to small species of robust habit, tlie body spheroidal to 

 broadly ellipsoidal, with broad apices, its length and width almost equal or its length may reach 

 1.27 transdiameters. In cross-section the body shows a slight dorsoventral flattening. This, 

 however, seems to be an unusual condition. The hypocone exceeds the epicone in size, its length 

 being greater "By 0.3. The epicone has an outline of something less than a hemisphere, with 

 broad, smoothly rounded apex. It has a length on the left and right sides of 0.28 and 0.38 

 respectively of the total length of the body. The posterior half of the hypocone is hemispherical 

 in shape, the sides of the anterior half being subparallel. The apex is broad and rounded. In 

 figure 42, plate 4, the body is slightly distorted in outline as though from the result of pressure 

 obliquely on the surface. Text figure AA, 9, gives a better outline of the normal individual. 



The girdle is premedian in position, its distance from the apex at the proximal end being 

 about 0.28 and at its distal end 0.38 of the total length of the body. Its path around the body 

 is that of a descending left spiral, displaced posteriorly its own width or slightly more. The 

 furrow is wide, about 0.06 transdiameter, and is deeplj' impressed. The anterior lip is under- 

 cut, the posterior side of the furrow gradually rounding out to the surface of the body. The 

 borders of the girdle are marked by the undulations of the surface of the body or they may be 

 smooth. The sulcus may invade the epicone only a short distance or may reach nearly to the 

 apex. The anterior flagellar pore is located at the proximal junction of the girdle and sulcus, 

 the posterior pore a short distance below. 



