KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 377 



Dimensions. — Length, 30-40/^; transdiameter, 13-18/*; diameter of nucleus, 

 7-9m. 



Occi'KRENCE. — The first individual of this sijeeies was taken July 20, 1917, 

 in a haul made 6 miles off La Jolla, California, from 80 meters to the surface 

 in a surface temperature of 20-5 C. The dividing specimen was taken in a 

 similar haul 4 miles off La Jolla in a surface temperature of 20'?8 C. The 

 species was also taken August 3, 6.5 miles off La Jolla in a haul from 80 meters 

 to the surface at 21-2 C and August 13, 0.75 mile offshore in a haul from 83 

 meters to the surface at al)out 22?5 C. Miss Lebour (1917Z>) reports a single 

 individual in Augiist, 1915, from the plankton of Pl}inouth Sound from a 

 water sample taken from a depth of 7 fathoms. 



Acxn'iTiEs. — Encysted forms are incessantly active, rotating within the ej'st, 

 both flagella being active. 



Comparisons. — ]Miss Lebour describes her specimen as colorless, fusiform 

 in shape, with, a girdle of three turns and sulcus making over one turn around 

 the body. She states that its length is 50/* and tliat of the cyst 650/^ [sic] . 

 These dimensions do not agree with the measurements of her figure which has 

 a length of 60/* and a width of 21/*, Avhile the length of the cyst is only 85/*. Her 

 figure is evidently reversed, as it shows the organism with a complete reversal 

 of organelles, its girdle and sulcus liaving a right instead of left descending 

 course (see Kofoid and Swezy, 1917). The sulcus or longitudinal furrow makes 

 2.5 turns around the body rather than "over one" turn, as she has stated. 



This is the smallest species of CocModuiium, although not the shortest, thus 

 lying at the opposite extreme from C. augustum (fig. HH, 15), the nearest 

 related species and the only other one in the suligenus Pohicliniiim. C. pul- 

 chelhim has 0.5 less turn of the sulcus than C. augustum and an oblujue instead 

 of a vertical antapical extension of the sulcus beyond the posterior junction 

 with the girdle. Otherwise the principal difference between the two species is 

 in size. 



Cochlodinium radiatura sp. nov. 



Plate 6, figure 67; text figure GG, 12 



Diagnosis. — This is a medium sized species with rotund elli])s<)idal Ixxly, 

 its length 1.28 transdiameters ; girdle a descending left spiral of 2 tuins. dis- 

 placed 0.75 transdiameter; sulcus with torsion of 1 turn; color, glaucous blue 

 splashed with aster purple. Length, 68/*. Pacific off La Jolla, California, July, 

 August. 



Descriptiox. — The body is of robust habit, rotund ellipsoidal in shape, circular in eross- 

 section, with broad rounded apices, its length 1.28 transdiameters at the widest part at the 

 middle. The epicone exceeds the hypocone in size, its length being greater by 0.3 of its own 

 length. It is subhiinispherical in shape, with a length from the proximal and distal ends of 

 the girdle of 0.33 and 0.91 respectively of the total length of the body. The posterior portion 

 is a wide band which diminishes distally to a slender point after making a nearly complete turn 

 about the body. The anterior part of the hypocone is wider than the corresponding part of the 

 epicone, becoming narrower near the posterior pore. It is broadly rounded distally with the 



