NOTES ON DINOFLAGELLATES. 29 



This description differs from that given by Kofoid in the 

 following points : Fewer details as to cell contents, accurate 

 dimensions, surface striations, etc., have been observed in the 

 British specimens, which are considerably larger and less 

 deeply coloured than those occurring on the Californian coast. 



Gymnodinium agile, Kofoid. Individuals of this species 

 have occurred from time to time in scrapings from the south 

 end of the beach, though they are never abundant. 



Description. Body rounded in ventral view, 

 flattened dorsoventrally. Epicone and hypocone subequal. 

 Epicone hemispherical with the apex displaced to the left as a 

 minute, pointed, finger-like projection bending downwards 

 towards the surface of the body. Hypocone symmetrically 

 hemispherical in ventral view. Girdle equatorial and without 

 displacement. Sulcus extending from girdle to antapex. 



Position of nucleus uncertain. Cytoplasm clear and 

 colourless. Minute refractile bodies numerous in epicone and 

 absent in hypocone where a single large amyloid body (?) is 

 present. No chromatophores. Length about 30//. 



So far as this description goes it agrees with that of Kofoid 

 for G. agile taken from beach sand at La Jolla. In the 

 Californian form, however, there are coral-red pusules and 

 orange green chromatophores. 



Gymnodinium placidum, sp. nov. This species occurred 

 frequently, though never abundantly, in the inner harbour 

 during 1920-1922, especially in the trickle of water draining 

 down from under the harbour steps. Movements slow and 

 deliberate. 



Description. Body ellipsoidal and dorsoventrally 

 flattened, its length 1*5 transdiameters and its dorsoventral 

 diameter about half its transdiameter. Ventral surface more 

 flattened than dorsal. Epicone, slightly longer than hypocone 

 tapering anteriorly and expanding slightly posteriorly s<o as to 

 form a thickened anterior rim to the girdle. Hypocone bemi- 



