KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 297 



Gyrodinium cuneatum nom. sp. nov. 



Text figure CC, 17 

 Gymnodinium gracile, Poueliet (18S5a), pp. 69-71, pi. 4, figs. 32, 33. 



Diagnosis. — A large species Avith obovate or cuneiform l)ody, its length 1.72 

 traiisdiameters ; girdle a descending left spiral, displaced 0.6 transdianieter ; 

 sulcus extending from apex to antapex; epicone striate; color, rose. Length, 

 100/^. Atlantic off Concarneau, France. 



Description. — Tlie body is obovate or cuneiform in shape, widest anteriorly, its length 1.72 

 transdiameters at the widest part, which is at the girdle. The hypocone exceeds the epicone in 

 size, being nearly twice its length. The epicone has the shape of a broad, low cone of about 100° 

 with the apex sliglitly notched (by the anterior end of tlie sulcus?). It has a length on the left 

 and right sides of 0.37 and 0.7 respectively of the total length of the body. The increase iu 

 length is confined to tlie right side of the ventral surface where it is drawn out posteriorly in a 

 long slender point. The hypocone lias an elongate campanulate shape, flaring at the region of 

 the girdle and symmetrically rounded posteriorly. 



The girdle is preinedian for most of its length, with a distance from the apex at its proximal 

 and distal ends of 0.37 and 0.7 respectively of the total length of the body, having a displacement 

 of 0.6 transdiameter. It passes around the body in a transverse plane for about 0.75 of the 

 circuit, turning posteriorly at a rapidly steepening angle which becomes about 15° with the 

 longitudinal plane, at its point of union with the sulcus. The furrow has a width of about 0.06 

 transdiameter, and is deeply impressed with overhanging borders. The sulcus probably begins 

 at the notch at the antapex and passes posteriorly as a slender, obscure trough in a nearly 

 straight line to the antapex. The longitudinal flagellum arises a short distance beyond the distal 

 junction of the girdle and sulcus. The transverse flagellum is not figured by Pouchet (1885a). 



The nucleus is ellipsoidal and located near the posterocentral part of the body. Its major 

 and minor axes are about 0.26 and 0.48 transdiameters respectively in length. 



The central part of the cytoplasm is occupied by a mass of yellow-orange granules of varying 

 sizes, larger in the center and smaller peripherally. Large colorless vacuoles are present in the 

 epicone with a few in the antapical region. The general color of the body is a transparent rose 

 diffused through the cytoplasm. The surface of the epicone is marked by longitudinal striae 

 which fade out near the apex and girdle. 



Dimensions.— Length, 90-100a* ; transdiameter, 58/^ ; axes of nucleus, 28/^ and 

 17m. 



Occurrence. — Figured by Pouchet (1885«) from the Atlantic off Concar- 

 neau, France. 



Synonymy. — This form was figured by Pouchet as Gymnodinium gracile 

 Bergh. It differs, however, from that species in its lack of a differentiated 

 ectoplasm, absence of striae on the hypocone, and in the greater dis])lacenient 

 of its girdle. This latter feature removes it from Gtjmnodinium, and we, there- 

 fore, place it in Gyrodinium as G. cuneatum nom. sp. nov. 



