KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 355 



DiJiTA'Sioxs. — Length, 108^*; transdiameter at the widest part of the body, 

 47;"; axes of nucleus, 25/^ and 16/^. 



Occurrence. — Two individuals were taken August 13, 1917, with a No. 25 

 silk net in a haul 0.75 mile off La Jolla, California, from 83 meters to the 

 surface, in a surface temperature of 21°9 C. 



Co:\[PARisoxs. — There are only four species of this genus larger than C. 

 august iDn, to wit: C. atromaculatuni, 184/^; C. distortum, 156/^; C. miniafmn, 

 200/^; and C. strnngulatum, 200^^. This species has more torsion than any known 

 member of the GjTnnodinioidae, or of the Dinofiagellata as a whole. The 

 nearest to it is in C. jmlchcJIu))! Lebour (fig. HH, 16) with a toi-sion of its 

 sulcus of 2.25 turns to the 3.1 turns of C. angustum. It is the most specialized 

 member of the subgenus PoJijdiuium and one of the most differentiated in 

 Cochlodimwn also. Its specialization is also indicated by its large size. The 

 nine different channels which cross the "ventral" face of this organism are so 

 close to each other and divide up the surface so completely that there must be 

 considerable stretching and distension of adjacent regions wherever the animal 

 feeds on an object as large as the food ball figured in our specimen. 



Cochlodinium catenatum Okamura 



Plate 9, figure 105 ; text figure GG, 14 

 Cochlodinium catenatum Okamura (1916), p. 41, figs. 1-3. 



Diagnosis. — A minute species with rotund ellij^soidal l)ody, its length 1.29 

 transdiameters ; girdle a descending left spiral of 1.5 turns, displaced 0.7 trans- 

 diameters ; sulcus with torsion of 0.5 turn ; color, light yellowish green to yellow 

 ochre ; tending to form colonies. Length, 35/^. Pacific off La Jolla, California, 

 July, August ; Yokohama Harbor, Japan, Jtuie. 



Description. — The body is rotund ellipsoidal with broad, rounded apices, nearly circular in 

 cross-section, its length 1.29 transdiameters at the widest part, which is at the middle. The 

 epieone and hypocone are subequal in size. The epicone is subhemispherical anteriorly with 

 broad symmetrically rounded apex. It has a length from the proximal and distal ends of the 

 girdle of 0.25 and 0.80 respectively of the total length of the body. The hypocone is also sub- 

 hemispherical in shape with broad antapex slightly notched by the distal end of the sulcus. 



The girdle is a descending left spiral of 1.5 turns, distant from the apex at its proximal and 

 distal ends about 0.25 and 0.8 respectively of the total length of the body, with a displacement 

 of 0.7 transdiameter. The furrow has a width of about 0.07 transdiameter and is deeply 

 impressed with smooth, rounded sides. The sulcus invades the epicone to near the apex as a 

 slender trough which fades out anteriorly. Posteriorly it is deflected to the left below the 

 proximal junction with the girdle, with a torsion of 0.5 turn in the intercingular area before 

 meeting the distal end of the sulcus, beyond whicli it takes a nearly straiglit course to the 

 antapex. The anterior flagellar pore opens at the proximal junction of the girdle and sulcus, 

 the posterior pore at the distal angle of the posterior junction. 



The nucleus is spheroidal and is located near the center of the body. Its axis is about 0.5 

 transdiameter in length. 



The cytoplasm is finely granular, clear and transparent, and contained no vacuoles or other 

 cell inclusions in tlie individuals examined, while another contained a small, partly digested 



