KOPOID AND SWEZY: UNARMORED DINOFLAGELLATA 145 



Amphidinium lacustre Stein 

 Text figure U, 15 



Amphidinium lacustre Stein (1883), p. 15, pi. 17, figs. 21-30. 



A. lacustre, Biitsehli (1885), pp. 940, 993, pi. 54, fig. 7. 



A. lacustre, Pouehet (1885), p. 54. 



A. lacustre. Schilling (1891), p. 62; (1913), p. 14, fig. 9. 



A. lacustre, Mez (1898), p. 217. 



A. lacustre, Ludwig (1898), p. 299. 



A. lacustre, Sdionicheu and Kalberlah (1900), p. 230, pi. 8. fig. 2; (1909), p. 251, pi. 8, 



fig. 2. 

 A lacustre, Lemmermann (1900), p. 115; (1903). p. 260; (1910), pp. 580, figs. 8-13, 616, 



617. 

 A. lacustre, Zederbauer (1904), p. 2. 

 A. lacustre, Senft (1905), p. 89, figs. 42-48. 



A. lacustre, Liebetanz (1905), p. 36; (1910), p. 42, pi. 2, fig. 39. 

 .4. lacustre, Kofoid (1907a), p. 301. 

 A. lacustre, Entz (1907), p. 24; (1909), p. 262. 

 A. lacustre, Ohno (1911), p. 91. 

 A. lacustre, Herdman (19116), p. 39; (1911c), p. 72. 

 A. lacustre, France (1912), p. 28. 



Diagnosis. — A minute species with broadly ovoidal body, its lengtli 1.25 

 traiisdianieters, antapex rounded ; girdle anterior, without displacement ; sulcus 

 extending from girdle to antapex; brown chromatophores. Length, 23/^. Fresh 

 water and brackish pools in Eurojje and Japan. 



Description. — The body is rotund ovoidal, rounded posteriorly, almost flattened anteriorly, 

 its length 1.25 transdiameters at the widest part. The epicone forms only a minute portion of 

 the body, its length 0.13 of the total length of the body and its widtli about 0.52 transdiameter 

 of the body. It forms a small rounded or somewhat flattened operculum-like lid separated from 

 the rest of the body by the broad girdle. The hypoeone is heart-shaped in ventral view, its length 

 about 0.78 of the total length of the body, with a broad rounded antapex. 



The girdle is anterior, forming a complete circle around the body about 0.13 of the total 

 length of the body from the apex. The furrow is about 0.1 transdiameter in width, and deeply 

 impressed. The sulcus is a furrow extending from the girdle to the antapex, wide anteriorly 

 and narrowing posteriorly. A thickening occurs on the right border at the proximal end. Stein 

 does not figure a transverse flagellum. The longitudinal flagellum arises at the junction of the 

 girdle and sulcus at a point marked by the presence of a spherical pusule. 



The cytoplasm contains numerous minute spherules and several larger brownish chromato- 

 phores. No nucleus has been figured by Stein. 



Dimensions. — Length, 23/*; transdiameter, 18/*. 



OccuERENCE. — Figured by Stein (1883) from fresh-water ponds and ditches 

 near Prague, Austria. The only other records of its occurrence are those of 

 Daday (Schilling, 1913, p. 14), who observed it in brackish pools near Deva, 

 Hungary, and Liebetanz (1910), who records its appearance in the stomach 

 contents (Panseninhalt) of four cows at Bern, Switzerland. All published 

 figures subsequent to those of Stein (1883) appear to be based on those of that 

 investigator. 



