KOFOID AND SWEZY: UNARMORED DINOPLAGELLATA 255 



Gymnodinium scopulosum sp. iiov. 



Plate 1, figure 7 ; text figure X, 6 



Diagnosis. — A small species with obovoidal to subbicouieal body, its length 

 1.8 traiisdiameters ; girdle submedian in position, displaced 0.3 transdiameter ; 

 sulcus extends' from near apex to antapex; color, oil yellow. Length, 47/*. 

 Pacific ofE La Jolla, California, August. 



Description. — The body is obovoidal, widest anteriorly, tapering slightly at both apices 

 which are rather broad, its length 1.8 transdiameters at the widest part. The epicone exceeds 

 the hypocone in length by 0.11 of its own length, and in transdiameter by 0.21 of its own trans- 

 diameter. It forms an overhanging, craglike dome with rounded sides and slightly tapering 

 apex. It has a length on the left and right sides of 0.4 and 0.56 respectively of the total length 

 of the body. The hypocone is more slender than the epicone, tapering more posteriorly with a 

 narrow antapex. 



The girdle is submedian in position. Its proximal end joins the sulcus at a distance from 

 the apex of 0.4 of the total length of the body. It passes around the body in a descending left 

 spiral course, its distal end meeting the sulcus at a distance from the apex of 0.56 of the total 

 length of the body, displaced 0.3 transdiameter. The furrow has a width of about 0.09 trans- 

 diameter and is deeply impressed, undercutting the anterior border and smoothly curving out 

 to the posterior one. The anterior border projects far out beyond the posterior border. The 

 sulcus begins a short distance below the apex and extends posteriorly in an almost straight line 

 to the antapex. The anterior flagellar pore opens at the proximal junction of the girdle and 

 sulcus, the posterior pore midway between the distal junction and the antapex. 



The nucleus is a small ellipsoidal body lying in the left side of the epicone. It is filled with 

 coarse, moniliform chromatin strands following its longest diameter. Its nmjor and minor axes 

 are 0.53 and 0.36 transdiameters in length respectively. 



A small saeklike pusule opens into each flagellar pore. The cytoplasm is very finely granular 

 and contains few iuelusions. such as vacuoles and food bodies. Near the posterior end of the 

 nucleus one large pink vacuole and a number of small, blue-green ones were present in the 

 epicone. The color of the cytoplasm presents a mi.xture of blue gi-een, oil yellow, and pearl 

 grey, with deeper tones of oil yellow on the sides and at both ends. A thin, hyaline cyst, 

 considerably larger tlian the body, enclosed the organism. 



DiMEXSioxs. — Length, 47/^ ; transdiameter, 26h- ; axes of nucleus, 14/* and 9/* ; 

 length of cyst, 52/*; transdiameter of cyst, 38/*. 



OccuBRExCE. — Two individuals were taken August 6, 1917, in a haul 4 

 miles off La Jolla, California, from 60 meters to the surface and in a surface 

 temperature of 21-2 C. 



CoiMPABisoNS. — This species belongs to the subgenus Gymnodinkim sensu 

 strictu, characterized by a thin periplast without surface markings. It is close 

 to G. Junnla. but is larger, has more tapering apices, greater disproportion of 

 epicone and hypocone, and straighter sulcus. Nothing is known of ' ' pjTocystis ' ' 

 stages of this species. 



