212 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA 



The girdle is subequatorial in position and forms a complete circle around the body -n-ithout 

 displacement. The furrow is shallow and about 0.08 transdiameter in width with smooth borders. 

 The sulcus begins at the girdle and extends posteriorly to the antapex in a straight line. 



The nucleus is a small, spherical body near the anterior part of the epicone. Its diameter 

 is about 0.2 transdiameter of the body in length. Numerous small, yellow brown chromatophores 

 fill the peripheral zone of the cji:oplasm. 



DiMENSioisrs. — Length, 80-100/'; transdiameter, about 58m: axis of nucleus, 

 12/^. 



OccFRREXCE. — Described and figured liy Ehrenberg (183J:, date of separate 

 publication) from fresli water in the vicinity of Berlin. May 4. Other records 

 of its appearance are as follows: In Lake Plon, Germany, by Apstein (1896) 

 in April-June, by Zacharias (1896\ and Ijy Leimuermann (1903) in March; 

 by Stein (1883) near Chodau, Austria, and near Budapest, Htmgary, by Entz 

 (1896) : l)y Wesenliurg-Lund (1904) in all the Zealand and Jutland lakes in 

 Demnark, from ^lareh to October ; in Stor-Pentida Lake, Finland, ]\v Levander 

 (1900) in July; near Basel, Switzerland, by Schilling (1891), in Katzen Lake, 

 Zurich, Switzerland, by Amberg (1900), and in Brazil by Cunha (1913). 



Synonymy. — Described by Ehrenberg (1834) as Peridiuium fusciim, the 

 name was changed by Stein (1878) to Gjjmnodinium fuscum. It is the type 

 species of the genus, being the first one named and figured by Stein. 



liEL.'VTiONSHirs. — Tliis species belongs to the small group of fresh-water 

 Gijrnnodiuium characterized by the possession of yellow or yellow ochre chro- 

 matophores, and falls in the subgenus Gijmnodininm seiisii strictu. It is nearest 

 related to G. Diirahile in size and general proportions. 



Gymnodinium fusus Scliiitt 



Text figure X, 5 



Gymnodinium fusus Schiitt (1895), pi. 21, fig. 79, pi. 25, fig. 81 (in part, pi. 25, fig. 81, is 



Gyrodinium falcatum sp. nov.) ; (1896), p. 5, fig. 5 D. 

 G. fusus, Karsten (1907), p. 310. 

 G. fusus, Entz, Jr. (1907), p. 11; (1909), p. 246. 

 G. fusus, Klebs (1912), p. 390. 

 G. fusus, Lemmermann (1910), p. 618. 



Diagnosis. — Large sized species with spindle-shaped body, its length 2.06 

 transdiameters ; girdle slightly premedian, its ends displaced its o^ti width; 

 sidcus extending from near the apex to the antapex; yellow-lirown chromato- 

 phores. Length, 122/^. Mediterranean or Atlantic, Arctic, Indian oceans. 



DESCRrPTioN". — The body is stout spindle-shaped, widest at the middle and tapering towards 

 both ends, its length 2.06 transdiameters at the widest part. The hypocone exceeds the epicone 

 in length by 0.15 of its own length. The epicone has a length on the left and right sides of about 

 0.39 and 0.4-1 respectively of the total length of the body. It is conical (45°) with sides irreg- 

 ularly sloping from the blunt apex to the girdle in ventral view. The hypocone is slightly 

 broader (50°) and is less symmetrical. In lateral view the ventral side of the epicone is concave 

 and of the hypocone convex, sloping abruptly to the narrow antapex. 



