KOFOID AND SWEZY: UNARMORED DINOPLAGELLATA 155 



Comparisons. — The flattened epicone of this species suggests those of A. 

 operculatum, A. scissmn, and .4. herdinaiii (figs. U, 25, 1, 2), the last having the 

 greatest resemblance. It is qnite distinct from these species, however, in the 

 form of ei^icone, the well developed pellicle, proportions of the body, and the 

 striate hypocone. 



Amphidinium turbo sj). nov. 



Plate 9, figure 98 ; text figure U. 1 6 



Diagnosis. — A minute species with broadly ovoidal ))ody; length 1.38 trans- 

 diameters, apex and antajiex subacute; girdle anterior without displacement; 

 sulcus very short ; color pearl grey. Length, 23/^. Pacific oft La Jolla, Cali- 

 fornia, July. 



Description. — Tlie b(xly is broadly ovoidal, widest in front of the middle part of the body, 

 its length 1.38 transdiameters at tlie widest part. The epicone is a minute peaked, eaplike portion 

 surmounting the broad girdle. It has a length of 0.13 of the total length of the body. It is 

 broadly conical in shape, forming an angle of about 110°, with the apex excentrically placed 

 slightly to the left. The hypocone is cordate-shaped in ventral view and symmetrically rounded, 

 with slight tendency to a subacute point at the antapex. 



The girdle is broad, about 0.15 transdiameter and deeply impressed. It is placed far 

 anteriorly and the transdiameter in it is about 0.4 of the broadest transdiameter of the body. 

 It forms a complete circle around the body. The anterior flagellar pore is located near the 

 posterior border of the girdle at the left of the median line. The post(M-ior pore is located about 

 one width of the girdle below the anterior pne. The sulcus is a short Y-shaped depression below 

 the anterior flagellar pore. Its length is nearly twice the diameter at the girdle. 



The large, spheroidal nucleus is found in the central part of tlie body. Coarse moniliforiii 

 chromatin strands, eight across one face, are prominent in its structure. Its axis is about 0.5 

 transdiameter in length. 



The cytoplasm is very clear and transparent without ajiparent granulations. Its color is 

 pearl grey. The pellicle of the hypocone appears as a double-contoured line. The cytopla.sm 

 contains numerous, blue green spherules and more minute granules. The epicone appears to be 

 destitute of these. No striations or other markings could be detected on the surface. 



Dimensions. — Length, 23/^; transdiameter, 17/*; axis of nucleus, 9/^. 



Occurrence. — Two individuals were oliserved in tlie collections made in the 

 Pacific off La Jolla, California, in 1917. These Avere taken July 5, with a No. 12 

 silk net, in a haul 6 miles off La Jolla, from 80 meters to the surface and in a 

 surface temperature of 21 ?9 C. On July 25 another was noted in a haul made 

 11 miles offshore, from 80 meters to the surface and in a surface temperature 

 of 21?7 C. 



CoisiPARisONS. — This form shows a strong reseml)lance to .4. lacustre Stein. 

 Stein's (1883) species is fomid in fresh and brackish waters and possesses 

 brownish chromatophores. It may 1)(> that our foi-iii is the marine representative 

 of the same species. 



