KOFOID AND SWEZY: UNARMORED DINOPLAGELLATA 299 



Gyrodinium falcatum noni. sp. nov. 

 Text figure CC, 11 

 Gymnodinium fusus Schiitt (1895), in part, including onh' fig. 81, pi. 25. 



DiAGXosis. — A large species with irregular, spiudle-shaped body, its length 

 1.87 transdiameters ; girdle suhniedian, a descending left spiral, displaced 0.39 

 ti'ansdiameter; sulcus short on both hypocone and e])icone; yellow ochre chro- 

 matophores. Length, 121/^. Atlantic (?) or Bay of Naples. 



Description. — The body is irregularly spindle-shaped, concave dorsally, nearly straight ven- 

 trally, its dorsoventral and transverse diameters subequal, its length 1.87 transdiameters at the 

 widest part. It is broadly rounded in the middle, and contracted into narrower processes at 

 both ends. The epicone is slightly larger than the hypocone, its length being greater by 0.11 of 

 its own length. It is roughly subconical in shajie, rotund posteriorly, deeply contracted midway 

 between the girdle and the apex, forming an irregular lobe anteriorly with convex sides with a 

 width of 0.41 transdiameter and a truncate apex. It is somewhat a.symmetrical with the anterior 

 lobe slightly deflected to the right. It has a length on the left and right sides of 0.41 and 0.62 

 respectively of the total length of the body. The hypocone is less irregular than the epicone, 

 rotund anteriorly with the posterior lobe shorter and the antapex more rounded than in the 

 epicone. 



The girdle is submedian in position, its proximal end joining the sulcus at a distance from 

 the apex of 0.41 and its distal end 0.62 respectively of the total length of the body. It sweeps 

 around the body in a descending left spiral course, displaced posteriorly 0.39 transdiameter. 

 The furrow has a width of about 0.06 transdiameter, and is deeply impressed with smoothly 

 rounded borders. The sulcus is short on botli epicone and hypocone, is deeply impressed in the 

 intercingular area, soon fading out towards both apices. The flagella and pores were not figured 

 by Schiitt (1895). 



The body is completely filled with stout rodlike, yellow ochre chromatophores and spheroidal 

 bodies closely crowded together. Nucleus and pusules were not figured by Schiitt. The pellicle 

 is double contoured. The organism was surrounded by a cyst which conformed to the shape of 

 the body but was somewhat larger in size. 



Dimensions. — Length, 121^; transdiameter, Qdi--; length of cyst, 175/*. 



OccuERENCE.— Figured l)y Schiitt (1895) from material collected by the 

 Plankton Expedition, presumably from the Atlantic or from the Bay of Najjles. 



Syxoxymy. — Schiitt (1895) on his plate 24, figure 79 (our text tigure X, 5), 

 portrays Gymnodinium fusus, a form which is evidently a true Gymnodinium. 

 On his plate 25, figure 81 (our text fig. CC, 11), he gives the same name to 

 another organism which has the Gyrodinium type of girdle, with approximately 

 the same size as the first form. "While the comparative length and breadth may 

 vary considerably in the species or even in the same individual, corres])onding 

 to different states of contraction and expansion, yet this does not affect the 

 displacement of the girdle, the intercingular area remaining nearly constant. 

 The girdle displacement in his second figure (our text fig. CC, 11) is greater 

 tlian one-fifth the total length of the body; we therefore place it in tlie genus 

 G yrodinium as G. falcatum. Schiitt's figure 8I2, plate 25, is inverted, sliowing 

 a reversed relation to that in his figures 81 1 and 8I3. The absence of the flagella 



