318 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA 



DiMEXSiON^s. — Length, 61-67a*; transdiameter, 43^7/^; transdiameter of 

 uueleus, 19m. 



OccuRBExcE. — Two individuals only of this species were observed. The first 

 was taken on July 21, 1917, in a surface haul at the end of the j^ier at the 

 Biological Station at La Jolla, California, with a No. 25 silk net. The second 

 individual was taken July 22 at the same place and with the same apparatus. 



CoMPABisoNS. — The coincident presence of chromatophores and food bodies, 

 evidence of both holozoic and holopliAiiic nutrition, is not an unknoT\Ti phenom- 

 enon in the Gymnodinioidae. The same thing is found in Ampliidinium steini 

 (Stein, 1883, pi. 17, figs. 14—16), Gymyiodinium favum sp. nov., G. ravenescens 

 sp. nov., G. fulgens sp. nov., and G. herhaccum sp. nov. (figs. X, 7, 21, 30; Y, 17). 

 The presence of chromatophores is relatively rare in this genus, onl}^ three 

 other species possessing them, G. falcatum sp. nov., G. foliaceum sp. nov., and 

 G. pusillum (Schilling) (fig. CC, 11, 18, 3). It is close to G. foliaceum (fig. CC, 

 18), but is larger, with more displacement of the girdle and torsion of the body. 



Gyrodinium mitra noni. sp. nov. 



Text figure EE, 5 



Gymnodinium spirale var. mitra, Schiitt (1895), pi. 21, fig. 68a. 

 Spirodinium spirale var. mitra, Lemmermann (1899), p. 359. 



Diagnosis. — A rather small. species with an as\inmetrical subfusiform body, 

 its leng-th 2.6 transdiameters ; girdle a descending left spiral, displaced 1.17 

 transdiameters ; sulcus joining ends of girdle. Length, 78/*. Atlantic or Bay 

 of Naples. 



Description. — The body is asymmetrical subfusiform, with a greater convexity on the right 

 side of the epicone, tapering towards both apices, its length 2.6 transdiameters at the widest part 

 which is anterior. The epicone exceeds the hypocone in size, its transdiameter being slightly 

 greater and its length greater b.v 0.15 of itself. It is asymmetrical, the right side convex and 

 the left nearly longitudinal, throwing the narrowly rounded apex strongly to the left. It has a 

 length on the left and right sides of 0.29 and 0.75 respectively of the total length of the body. 

 The hypocone is also asymmetrical, with a sigmoid outline on the left side, nearly straight on 

 the right, throwing the antapex towards the riglit, but with less deflection than in the apex. It 

 is narrower than the epicone with a slender blunt antapex. 



The girdle is a descending left spiral distant from the apex at its proximal and distal ends 

 about 0.29 and 0.75 respectively of the total length of the body. It is displaced about 1.17 

 transdiameters with a slight overhang. Its proximal end turns abruptly posteriorly at an angle 

 of 50° with the longitudinal plane of the body, until it reaches the left lateral border where it 

 turns and passes across the dor.sal face in an almost transverse direction, turning again poster- 

 iorly near the right lateral margin and traversing the right ventral face at an angle of about 

 55° with the longitudinal plane. The furrow has a width of about 0.14 transdiameter and is 

 deeply impressed with smooth borders. The sulcus in Schiitt 's (1895) figure does not extend 

 beyond the intercingular region where its width is nearly equal to that of the girdle. 



The nucleus is a rather large, ellipsoidal body, densely filled with short chromatin strands 

 and located in the anteroeentral part of the body. Its major and minor axes are about 0.75 and 

 0.5 transdiameters in length respectively. 



