KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 233 



The girdle is slightly premedian, its distance from the apex about 0.4 of the total length of 

 the body. It forms a complete circle around the body and is deeply impressed. The sulcus 

 extends from the girdle to the antapex in a straight line. The longitudinal flagellum arises at 

 the proximal end of the sulcus. 



The nucleus is not figured by Saville-Kent (1880-82). The cytoplasm is clear and trans- 

 parent and usually contains numerous spherules varying in size. Nutrition is holozoic. Saville- 

 Kent observed it actively devouring Hctcromifa and other monads in the same culture, the 

 organisms being taken in at the sulcal region near the girdle. 



Dimensions. — Length, 30i"; transdiametei^ 28/^; dorsoventral diameter, 17/^. 



OccTJERENCE. — Fig'ured })y Saville-Kent (1880-82) from an infusion of hay 

 and sea water made at St. Heliers, Jersey, in February. One month later the 

 culture was abundantly filled with these small holozoic forms. 



Comparisons. — This species finds its nearest relative, apparently, in G. 

 cinctum, a species with ochraeeous ehromatophores. G. cinctum, however, does 

 not show the same dorsoventral compression of the l)ody found in this species, 

 and has a smaller epicone. 



Gymnodinium minor Lebour 

 Text figure X, 12 

 Gymnodinium minor Lebour (1917&), p. 192, fig. 8. 



Diagnosis. — A minute species with stout ovoidal body, its length 1.16 trans- 

 diameters; girdle displaced by narrowing its furrow; sulcus extending from 

 the girdle to the antapex. Length, 28;*. Plymouth Sound, England, ]May-July. 



Description. — The body is rotund ovoidal with the widest part anterior, its length 1.16 

 transdiameters at the widest part. The epicone exceeds the hypocone in length by about 0.5 of 

 its own length. It is subhemispherical in shape with a length on the left and right sides of the 

 sulcus of 0.46 and 0.6 respectively of the total length of the body. The hypocone is slightly 

 narrower than the epicone with truncate antapex. 



The girdle is behind the midregion of the body, joining the sulcus about 0.64 of the total 

 length of the body from the apex. On the right side the furrow becomes contracted to less than 

 0.3 its own width, giving an appearance of displacement contradicted by the posterior borders 

 of the girdle. It is wide on the left side of the body, about 0.06 transdiameters, and deeply 

 impressed. The sulcus extends from the girdle to the antapex, widening as it passes posteriorly. 



The nucleus is an ellipsoidal body near the center of the body. Coarse chromatin strands 

 extend obliquely along its major axis. Its major and minor axes are about 0.5 and 0.25 trans- 

 diameter in length respectively. Several green food masses wore present in the anterior part of 

 the body. 



Dimensions. — Length, 28/' ; trausdiameter, 24/^ ; axes of nucleus, 12/^ and (h. 



Occurrence.— It has been figured by Lebour (1917&) from Plymouth Sound, 

 England, from collections made from May to July. 



Co^iiTARisoNS. — This species is nearest to G. ovnlum sp. nov. (fig. X, 15), 

 btit differs from it in the less spheroidal form (])roba))ly distended), greater 

 displacement of the girdle, and lack of sulcus on the epicone. 



