KOFOID AND SWEZY: UNARMORED DINOPLAGELLATA 295 



the total length of the body from the apex, being displaced 0.89 transdiameter. The furrow is 

 rehitively narrow, 0.06 transdiameter, and deeply impressed with recessed anterior lips and 

 rounded posterior border. Tlie sulcus begins at the proximal end of the girdle and extends 

 posteriorly to the antapex, as a narrow channel. Pores and flagella were not noted by Pouehet 

 (1885&). 



The nucleus is ovoidal and situated near the center of the body, but is not definitely shown 

 in position in Pouehet 's figiires (1885«., b). The cytoplasm is filled with large vacuoles with a 

 dark dense granular mass near its center. The surface is marked with broken (?) longitudinal 

 striae. The color is yellowish brown with a darker mass near the center. 



Dimensions. — Length, 120/^ to 200/i; transdiameter, 60/^ to 65^. 



OccuEEENCE. — Figured by Pouehet (1885rf, ft) from the Atlantic off Con- 

 carneau, France, from collections made in October and (1894) from the Arctic 

 Ocean near Si)itzl)ergen. The other records of its appearance are as follows: 

 Lebour (19176) from Plymouth Sound, England, in June. The form she de- 

 sci-ibes is considerably smaller than Pouehet 's, having a length of only 75/*. 

 Pavillard (1905) records it from the Gulf of Lyons in October and November. 



Synonymy. — Originally described from a single individual by Pouehet 

 (1885a) as Gj/miwch')iii())i cnissum. and again in the same year (1885?;, pi. 26, 

 fig. 2) he figures another individual assigned to G. crassum which differs from 

 the first figure in the dimensions and the clear indication of a median longitu- 

 dinal furrow without spiral course. His earlier figure (see his pi. 4, fig. 28) 

 showed a lateral, furrow-like indentation on the left side (of the figure), which 

 might be interpreted as indicating a spiral course of about 0.3 turn on the part 

 of the longittidinal furrow. However, he speaks of this longitudinal furrow 

 as being slightly undulating without specifying the course of the furrow which 

 is hidden in the figure. The probal)ilities are that the notch does not represent 

 a furrow and that the two figures refer to the same species. Both figures are 

 inverted. Lemmermann (1899) and later Paulsen (1908) refer the species to 

 Spirodinium. 



Comparisons. — The cytoplasmic structure of this species recalls that of 

 G Hmnodinhim dof/ieli and G. pacltydernHdum, without, however, having the 

 thickened periplast or ectoplasmic region of that species. The dark mass near 

 the center of the body is evidently formed of the dark, highly refractive granules 

 similar to those found in GijnniodiiiiiDn, and which are probably the metabolic 

 products of holozoic nutrition. 



Gijrodinium crassKin is the largest species in Gi/rodininm and significantly 

 is one with a northern distrilnttion, and found in the cooler part of the year. 

 It is not close to any other species in the genus in proportions or structure. 

 The nearest one appears to be G. ochracemn sp. nov. (fig. DD, 17), but the color 

 of the latter is far more brilliant, its sulcus has more displacement and torsion, 

 and the apices are different in the two species. 



