418 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA 



intercingular sulcus, but lies to the right and deep in the center of the body. 

 Its lens is also directed posteriorly. Its functional efficiency as an organ of 

 light perception can at the best be but slight. 



Protopsis nigra (Pouchet) 



Text figure LL, 1 



Gymnodinium polyphetnus var. nigrum Pouchet (1887), pp. 93, 97-104, 112, pi. 10, figs. 



2 A, B, 3, 4. Figures 2 C and 5 are not Protopsis nigra, but indeterminate. Figures 



inverted. 

 G. polyphemus var. nigrum, Sehiitt (1895), p. 95. 

 Pouchetia nigra, Lemmermann (1899), p. 360. 



P. nigra, PaviUard (1905), in part, pp. 47^8. P. juno tentatively included. 

 Gymnodinium polyphemus var. magna Dogiel (1906), p. 37. Lapsus for nigrum. 



DL4.GN0SIS. — A mediiun sized species, body as^nnniterical ovoidal, its length 

 1.5 transdiameters ; girdle equatorial, displaced 0.3 transdiameter ; sulcus 

 straight, midventral ; ocellus dispersed, mth 5-8 spherical lenses, amoeboid 

 black melanosome and red core; plasma ochraceous with scattered black 

 granules in periphery. Length, 74m. Coasts of France, spring and autimm. 



Description. — The body is asjTnmetrically ovoidal, its length 1.5 transdiameters; epicone 

 and hypoeone subequal. Epicone subhemispherieal, apex broadly rounded, nearly symmetrical, 

 less rotund at the right. Hypoeone a trifle smaller than the epicone. much less hemispherical, 

 prolonged at the right side, and with rounded autapex displaced to the left. 



Girdle equatorial, forming a descending left spiral displaced about 0.3 transdiameter and 

 not overlapping in the intercingular area. The furrow is deeph" impressed with prominent lips 

 and is about 0.12 transdiameter in width. The sulcus does not appear to be fully delineated. 

 As shown, however, it appears to be nearly straight, midventral, and not extended far upon the 

 epicone. It flares distally. 



The oeeDus is dispersed or compound, consisting of five to eight spherical lenses of varying 

 sizes and grouping and an amoeboid pigment mass with black, lobed melanosome and small, 

 brilliant red, centrally located core. It is located opposite the intercingular region of the sulcus 

 and does net appear to be protuberant or so close to the sulcus as in anj' way to modify it. The 

 peripheral plasma is crowded with black pigment in the form of small granules and coiled rods 

 in the form of commas, hooks, and irregular semicircles, somewhat more finely divided on the 

 right side of the epicone and less abundant near the melanosome, thus exhibiting a polarization 

 in the direction of the plane of fission. The nucleus is ellipsoidal with its major and minor axis 

 0.6-0.8 and 0.37-0.66 transdiameter in length respectively. It exhibits the typical parallel 

 chromatic threads. The general color is dark olive ochre, but distinct chromatophores are not 

 indicated. Pouchet (1887) notes the resemblance of its color to diatomin. Often encysted in 

 a closely fitting, transparent cyst. 



DiZkiExsioxs. — Length, 74m ; transdiameter, 45m ; length of ocellus, 15m ; diam- 

 eters of nucleus, 40m and 28m. 



OcciTRREXCE. — Abundant at Concarneau, France, in the marine plankton, 

 April 28 and May 2 and 3. PaviUard (1905) reports it (sensu latu) as rare in 

 the plankton of the Etang de Thau, at Cette, France, on the Mediterranean in 

 October and December. The surface temperatures range there from 18-4 C to 

 6-9 G in these months. 



