202 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA 



CoiMPAEisoxs. — This is one of the largest and at the same time most striking 

 members of the genus Gywnodinium. While it lacks the highly diiferentiated, 

 mammillated ectoplasm of G. paclijidermatum, it possesses a thick periplast of 

 much firmer consistency than the meml^ers of the other subgenera of the genus ; 

 it is therefore placed in the subgenus Pachydimum, near G. canus sp. nov., G. 

 coerulum, Dogiel, G. puniceum sp. nov., and G. ivilczeJci Pouchet, all with some- 

 what ribbed, coarsely striate surface (figs. X, 1, 4, 5, 8). It is the largest of the 

 group, lacks the contracted apex of G. canus, differs in color from G. coerulcum, 

 has a proportionally larger epicone than G. puniceum, and wholly different 

 proportions from G. wilczeki. 



Gymnodinium cucumis Sehiitt 



Text figure Y, 16 

 Gymnodinium cucumis Sehiitt (1895), pp. 100, 108, 111, 116, 117, pi. 21, fig. 64. 



Dtagxosis. — A large species with slender fusiform body, its length 3.24 

 transdiameters ; girdle with a descending left spiral course displaced about 2.5 

 of its o^^Ti width; sulcus extending from apex to antapes; surface striate. 

 Lengih, 210/*. Mediterranean at Naples or the Atlantic. 



Descbiption. — The body is long, slender fusiform, slightly wider posteriorly, tapering at 

 both ends, its length 3.24 transdiameters at the widest part. The epicone exceeds the hypocone 

 by about 0.39 of its own length. It is eonieal (32°) in shape, slightly asymmetrical with a 

 narrow, blunt apex. It has a length at its left and right sides of 0.55 and 0.6 respectively of 

 the total length of the body. The hypocone is broader (45°) with a narrow, blunt antapex. 

 Its length from the proximal and distal ends of the girdle is 0.4 and 0.32 respectively. The 

 dorsoventral and transverse diameters are equal. 



The girdle is postequatorial, meeting the sulcus proximally about 0.55 and distally 0.60 of 

 the total length of the body from the sulcus. It follows a descending left spiral course, displaced 

 posteriorly about 2.5 times its own width. It is a deeply imbedded furrow, 0.09 transdiameter 

 in width with overhanging, ribbed borders. The sulcus extends from the apex to the antapex 

 in an irregular line but with little or no torsion. The positions of the flagellar pores are not 

 shown in Schiitt's (1895) figures, though the longitudinal flagellum is shown, projecting from 

 the distal end of the sulcus. 



The nucleus is a relatively small, spheroidal body in the central part of the hypocone. Its 

 axis is 0.4 transdiameter in length. A large sacklike pusule extends along the transverse plane 

 of the body below the girdle, opening probably into one of the flagellar pores. A number of 

 food bodies were shown in one of Schiitt's figures (1895, pi. 21, fig. 64). The surface is striate 

 with a strong tendency towards the formation of ridges between the striae. 



DiMEXSioxs. — Leng-th, 211/*; transdiameter, 65/*; diameter of nucleus, 26/*. 



OccrRREXCE. — Figured by Sehiitt (1895) from the collections of the Plank- 

 ton Expedition, presumably from the Mediterranean at Naples or the Atlantic. 

 Its occurrence has not been recorded elsewhere. 



CoMPARisoxs. — This is the second largest species in the genus or even in 

 the G}Tiinodinioidae thus far descrilied, onie species only exceeding it in length, 

 G. dogieli, with a length of 212/*. In the presence of ribs between the striae on 



