190 MEMOIRS OF THE UNIVERSITY OP CALIFORNIA 



Gymnodinium biciliatum Obuo 



Text figure X, 14 

 Gymnodinium Mciliafum Ohno (1911), pp. 77-91, pi. 1, figs. 1-37. 



Diagnosis. — A mimite species Avith In-oadly ellipsoidal body, its length 1.31 

 transdiameters ; girdle without displacement ; sulcus short on epicone, extending 

 to near the antapex on h^^iiocone; color yelloAv brown. Length, 22m. Fresh- 

 water ponds in the Botanical Gardens at the Imi)erial University at Tokyo, 

 Japan. 



Description. — The body is broadly ellipsoidal with broad rounded apices, and its length is 

 1.31 transdiameters at the widest part. The hypocone exceeds the epicone in size, its length 

 being greater by 0.2. The epicone has a length of about 0.4 of the total length of the body. 

 The hypocone is subhemispherical posteriorly, with broad apex. 



Tlie gii-dle is premedian in position, its distance from the apex being 0.4 of the total length 

 of the body. The furrow is wide, 0.09 transdianieter, and deeply impressed, with high rounded 

 borders. The sulcus is a short shallow trough, its length about twice the width of the girdle. 

 The longitudinal and transverse flagella arise in close proximity to each other at the junction of 

 girdle and sulcus. Two longitudinal flagella are described and figured by Ohno (1911), hence 

 the specific name. 



The nucleus is not figured by him, but it evidently lies in the dark mass near the center of 

 the body. Numerous oil droplets are contained within the c.vtoplasm. The color is yellow brown. 

 Chromatophores appear to be centrally ma.ssed ellipsoidal bodies of yellowish brown color. At 

 cyst formation the body rounds up within an irregularly lobed, thorny, cellulose cyst. 



DiMENsioxs.— Length, 22.2/* (20.6-25/0 ; transdiameter, 16.9/* (12-21m). 



Occurrence. — Figured liy Ohno (1911) from fresh-water ponds in the 

 Botanical Gardens of the L^niversity at Tokyo, Jajjan, where it was most 

 abundant during the winter months. 



DiscFSSiON. — The presence of three flagella in this form, two of which are 

 longitudinal, if valid, is Avithout parallel in the Dinoflagellata, and this fact 

 raises the question of the correctness of Ohno's interpretation. The appearance 

 shoA\Ti in his figure 5, plate 1, is one coimnonly seen in living Gymnodinium. 

 The actively moving flagellum swings through an arc that is fairly constant 

 and forms a cone of rotation, the sides of which are .strongly marked and give 

 the appearance of two very distinct flagella. Watching these until the move- 

 ment slows down, however, the observer sees them resolve into a single flagellum. 

 The presence of three flagella in the stained specimen finds its parallel in condi- 

 tions during the mitotic period in other flagellates. In most if not all flagellates 

 the motor organelles are the first to exhibit signs of division, and this not infre- 

 quently results in a precocious outgrowth of the new flagella. In the material 

 studied by Ohno rapid multiplication was evidently taking place, both in 

 encysted and free swinnniug forms. The central part of the body is figured 

 only as a dark mass and hence offers no conclusive evidence either way for the 

 solution of this problem. It is evident, however, that Ohno's interpretation 



