356 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA 



Gymnodinium, and a few slender, blue green rodlets. Nutrition is liolozoic. The color is a 

 diffuse light yellowish green. No striae or other markings could be detected on its surface. In 

 figure 105, plate 9, a chain of four zooids is figured. These are the products of recent mitoses, 

 whicli have not yet separated. 



DiMEXSioxs. — Length, 35as transdiameter, 28-35/^; axis of niteleiis, 14-16/^. 



OccuRREXCE. — This was first seen July 12, 1917, when a single individual 

 and a chain of four zooids were taken with a No. 25 net in a haid 6 miles off 

 La Jolla, California, from 80 meters to the surface and in a surface temper- 

 ature of 20-6 C. On Jul}^ 18 it was again present in a haul 4 miles off'shore, in 

 a haul from 80 meters to the surface and a surface temperatiu'e of 20?8 C. 



Okamura (1916) described this species from the waters of Yokohama 

 Harbor, Japan, in June, 1910 and 1911, at which time it occurred so abundantly 

 that the waters were discolored a dark reddish bro^\^l and fish were found fioat- 

 ing on the surface in a dying condition. 



Syxoxymy. — Okamura has described minute linear or dotlike chromato- 

 phores, yellowish brown in color, in the forms he observed. These were not 

 present in the individuals foiuid at La Jolla and may possibly have been food 

 bodies or oil droplets. The two forms correspond so closely in other respects 

 that it seems inadvisable to separate them. 



CoMPARisoxs. — Chain formation as a result of rapid schizogony is not un- 

 conunon in the Dinoflagellata ; it may be temporary or permanent, and may 

 occur in both the naked and thecate forms. Many species of GonijauJax and 

 Ceratinm form temporary chains. One species of Gouj/aidax (Kofoid and 

 Rigden. 1912) and the two species of the genus PoJi/krikos form permanent 

 colonies. In Okamura 's material single individuals of Coclilodininm catcnainm 

 were rare, chains of 4, 8, 16, and intermediate numbers being common, showing 

 a strong tendency towards pennanency or true colony formation. 



This species belongs to the C. miniatum group of the subgenus Cochlodinium. 

 It is the smallest s^^nmet^ically ellipsoidal species in the genus, with the mini- 

 mum amount of torsion, and represents the most i^rimitive condition in CocMo- 

 diniiim in structure. 



Cochlodinium cavatum sp. nov. 



Plate 9, figure 93 ; text figure HH, 10 



DiAGXosis. — A medium sized species with body as}inmetrically reniform, 

 excavated ventrally, arched dorsally, with a right antapical lolie; length 2.25 

 transdiameters ; girdle a descending left spiral of 1.5 turns, disi^laced 0.61 total 

 length ; sulcus with apical and antapical loops, and a torsion of 0.5 turns, plasma 

 oil yellow. Length, 66,«. Pacific off La Jolla, California, July. 



Description. — The body is elongated, markedly concave on the ventral face and convex on 

 the dorsal, thus throwing both apices exceutrically ventrad. This gives to the body a twisted 

 reniform shape. The epicone exceeds the hypocone in length by 0.14 of the total length of the 



