176 MEMOIRS OP THE UNIVERSITY OF CALIFORNIA 



can be determined: Gijnnioflhu'um Iricmidafum Pavillard (1905), G. corpits- 

 cidum (Perty, 1852) Saville-Kent (1880-82), G. gracilc var. exiguum Pouehet 

 (1883), G. inerme (Schmarda) Saville-Kent, G. lachmanni Saville-Kent (1880- 

 82), G. lohmanni (Lohmann, 1908), G. monadicum (Perty, 1852) Saville-Kent 

 (1880-82), G. pimctatimi Pouehet (1887), G. rete Scliiitt (1895), G. simplex 

 Lohmaun (1908), G. tintinnicola Lohmann (1908), G. triangidaris Lebour 

 (1917&), G. monas (Ehrenberg, 1840), Saville-Kent (1880-82). 



In the following discussion of the species of the genus Gymnodinium an 

 alphabetical arrangement of both the valid and doubtful species has been 

 preserved solely as a matter of convenience : 



Key to the Species of Gymnodinium 



1. Periplast thin, without striae, or if present limited and few ....(subgenus Gymnodinium) 2 

 1. Periplast thin, with striae - (subgenus Lineadinium) 58 



1. Periplast thickened, surface striate or smooth (subgenus Pachydinium) 42 



2. Striae or furrows on epicone or hypoeone, not on both 3 



2. No striae 5 



3. Surface with furrows on epicone only contractum sp. nov. 



3. Surface markings in hypoeone only 4 



4. About 8 furrows on hypoeone sulcatum sp. nov. 



4. Hypoeone with 18-20 striae - herbaceum Kofoid MSS. 



5. Chromatophores present 6 



5. No chromatophores — - 22 



6. In fresh water, chromatophores green 7 



6. Chromatophores yellow or nearly so 9 



7. Girdle postmedian, chromatophores scattered musei Danysz 



7. Girdle submedian, disklike chromatophores crowding the periphery.. ..aeruginosum Stein 



7. Girdle median, rod-shaped chromatophores radially arranged 8 



8. Length, 35/u, viride Penard 



8. Length, 11 fi - varians Maskell 



9. Pseudopodia extended from sulcus zachariasi Lemm. 



9. Pseudopodia not known to occur 10 



10. Marine species 11 



10. Fresh-water species 



11 Large species, length over lOO^u 12 



11. Length less than 100,* 13 



12. Body bieonical, girdle medium length, 122,i, 2.1 transdiameters fusus Schiitt 



12. Body with conical epicone, girdle premedian, length 100^, 2.3 transdiameters 



fulgens nom. sp. nov. 



13. Girdle not displaced 14 



13. Girdle displaced at least its own width 16 



