122 MEMOIRS OF THE UNIVERSITY OP CALIFORNIA 



CoMrAEiso?sTs. — This genus has been generally accepted and -widely iised as 

 a primitive representative of the Dinoflagellata heeanse of its partially devel- 

 oped girdle. In view of the fact that it is a fresh-water geni;s, without, as yet, 

 any representative on the sea, it may be that the imperfect condition of the 

 girdle is really a degenerate rather than a primitive one. It has a descending 

 spiral, though incomplete, girdle, and in this particular is nearer Gijrodinium 

 than to Giimnodiuiiim. Klebs (1883) states that Hcmidinium has a cell mem- 

 bi'aue which swells in sulphuric acid and stains yellow in iodine, is finely gran- 

 ular and sometimes striate. It appears, however, to be no more than the pellicle 

 of the unarmored dinoflagellates. The matter should be more fully investigated. 

 The genus is tentatively included in the G^^nnodiniidae. 



Key to the Species or Hemidinium 



Epicone and hypocone subequal, proximal end of girdle deflected posteriorly nasutum Stein 



Epieone much smaller than the hypocone, proximal end of girdle deflected anteriorly 



ochraceum Levander 



Hemidinium nasutum Stein 



Text figure R, 4 



Hemidinium nasutum Stein (1883), pp. 91, 97, pi. 2, figs. 23-26. 



H. nasutum, Eyferth (1879), p. 19. 



H. nasutum. Saville-Kent (1880-82), p. 442. 



H. nasutum, Klebs (1883), pp. 348, 351, pi. 2, fig. 27; (1884), p. 739. 



H. nasutum, Daday (1884), p. 10. 



H. nasutum, Biitschli (1885o), p. 559, fig. 1; (18856), 1008, 1016, pi. 51, fig. 3. 



E. nasutum, Dalla Torre (1885), p. 272. 



H. nasutum, Schilling (1891a), pp. 243, 248, 274, 275, pi. 8, figs. 23-25, pi. 10, fig. 8. 



H. nasutum, France (1893), p. 139. 



n. nasutum, Levander (1894), p. 43; (1900a.), pp. 58, 64; (1901), p. 6. 



H. nasutum, Delage and Herouard (1896), p. 384, fig. 667. 



H. nasutum., Entz (1896), p. 22; (1897), pp. xxxi, 52; (1902), p. 126; (1904), pp. 8, 11. 



H. nasutum, Schiitt (1896), p. 4, fig. 3. 



H. nasutum, Butschinsky (1897), p. 195. 



H. nasutum, Ludwig (1898), p. 298. 



H. nasutum, Mez (1898), p. 217, pi. 6, fig. 286. 



H. nasutum, Schonichen and Kalberlah (1900), p. 230, pi. 8, fig. 1 ; (1909), p. 251, pi. 8, 



fig. 1. 

 H. nasutum, Lemmermann (1900), p. 115; (1901), p. 358; (1902), p. 260; (1906), p. 419; 



(1910), pp. 617, 618, 580, figs. 14-18. 

 H. nasutum, Zacharias (1903), pp. 237, 244. 

 E. nasutum, Paulsen (1908), p. 94, fig. 127. 

 E. nasutum, Kleiber (1911), p. 14. 

 E. nasutum, Senn (1911), p. 64, fig. 6. 

 E. nasutum. Cavers (1913), p. 182, fig. 9. 

 E. nasut^irn, West (1916), p. 75. 



