KOFOID AND SWEZY: UNAKMORED DINOFLAGELLATA 323 



Description. — The body is slender fusiform with rounded apices, its length 2.88 transdiam- 

 eters at the widest part. The epieoue greatly exceeds the hypocone in extent, its length being 

 greater by 0.46 of its own length. It has a length on the left and right sides of 0.51 and 0.87 of 

 the total length of the body. The dorsal side is somewhat less symmetrical than the ventral, 

 tapering more abruptly to the narrow, rounded apex. The hypocone is broader posteriorly than 

 the epicone with broad, rounded antapex. 



The girdle lies almost entirely posterior to the equatorial plane of the body. It meets the 

 sulcus at a distance from the apex of 0.51 of the total length of the body. It follows a descending 

 left spiral course around the body, displaced about 0.92 transdiameter, its distal end joining the 

 sulcus about 0.12 of the total length of the body from the antapex. The sulcus extends from the 

 proximal end of the girdle to the antapex as a rather deep furrow. 



The nucleus is a small, spherical body found in the median ventral part of the cytoplasm. 

 It is homogenous with clear, central, hyaline nucleolus. The body figured here by Gourret (1883) 

 is unlike the nuclei found throughout the Gymuodinioidae both in relative size and structure 

 and is probably a vacuole. The central part of the cytoplasm is granular and filled with oil 

 droplets, with a hyaline zone near the periphery. The organism is yellow in color. 



Di:mexsions. — No dimeusious are given by Cloitrret and tlie magnification 

 of liis figure could not be determined. 



OccuRREXCE. — Gourret (1883) figaired this species from the Gulf of 

 Marseilles, France. 



SYNONY^kiY. — This form was described by Gourret as Gymnodinium ovatum. 

 Its girdle arrangement exchides it from that genus and it is here placed with 

 Gyrodinium as G. ovatum (Gourret). 



CoMPARisoxs. — This species is near G. contort um (Schiitt), but differs from 

 it in having a displacement of the girdle of about 0.33 of the total length as 

 compared with 0.5 in G. contortum. 



Gyrodinium ovoideum sp. nov. 



Plate 9, figure 106 ; text figure CC, 6 



DjAGXosis. — A rather large species with rotund ellipsoidal body, its length 

 1.28 transdiameters; girdle a descending left sjjiral, displaced 0.37 transdiam- 

 eter ; sulcus extending from girdle to antapex ; color, dilute primuline yellow. 

 Length, 12t^. Pacific off La Jolla, California, May to August. 



Description. — The body is stout, rotund ellipsoidal with bi-oadl\- rounded apices, circular in 

 cross-section, its length 1.28 transdiameters at the widest part. Tlie epicone and hypocone are 

 subequal in size. The epicone is subhemispherical in outline, its size smoothly rounded and apex 

 broad. It has a length on the left and right sides of 0.34 and 0.61 respectively of the total length 

 of the body. The hypocone is also subhemi.spherical in shape without sulcal noteli at the antapex, 

 its length nearly approximating that of the epicone. 



The girdle is submedian in position, its proximal and distal ends meeting the sulcus at a 

 distance from the apex of 0.34 and 0.61 respectively of the total length of the body. It forms a 

 descending left spiral with its distal end displaced 0.37 transdiameter, and with a slight overhang. 

 The furrow has a width of about 0.07 trau.sdiameter and is deeply impressed with, smooth 

 rounded borders. The sulcus may invade the epicone for a short distance or may stop with the 

 proximal margin of the girdle. It extends posteriorly in a sinuous line as a shallow trough 

 which fades out near tlie antapex. The anterior flagellar pore is located at the proximal junction 

 of the girdle and sulcus, the posterior pore slightly posterior to the distal junction. 



