KOFOID AND SWEZY: UNARMORED DINOPLAGELLATA 243 



Gymnodinium pseudonoctiluca I'duchet 



Text fi^ire X, 35 



Gyynnodinium pseudonoctiluca Pouchet (1885a), pp. 71-75, 76, 82, pi. 10, figs. 34—37; 



(1892a), p. 87; (1892&), pp. 143-150, pi. 11, figs. 1-14; (1894), p. 169. 

 G. pseudonoctiluca, Biitschli (1879), pp. 1078, 1082. 

 G. pseudonoctiluca, Lemmermann (1899), p. 359; (1910), p. 619. 

 G. pseudonoctiluca, Ostenfeld (1903), p. 561. 

 G. pseudonoctiluca, Mingazziiii (1904), pp. 98, 99. 



G. pseudonoctiluca, Paulsen (1908), pp. 97, 99, fig. 135. After Pouchet (18926). 

 G. pseudonoctiluca, Jorgensen (1912), p. 10. 

 G. pseudonoctiluca, Faure-Preraiet (1914), pp. 41, 43, 44, 45, fig. 11. After Pouchet 



(1892&). 

 Not Gymnodinium pseudonoctiluca, Lebour (19176), p. 188, fig 3 {=^G. fulgens nom. sp. 



nov.). 



Diagnosis. — A large species with long, subcylindrieal body, its length 2.5 

 transdiameters ; girdle anteriorly located, turning posteriorly on ventral side; 

 sulcus extending from girdle to antapex; color greenish. Length, 116/^. 

 Atlantic, Arctic. 



Description'. — Tlie body is long, subcylindrical, the anterior end conical, the posterior 

 rounded, its length 2.5 transdiameters. The epicene is greatly exceeded by the hypocone in 

 extent, having an average length of less than 0.3 the length of the hypoeone. The length of the 

 epieone on the dorsal side is 0.18 of the total length of the body. It extends posteriorly on the 

 ventral side in a slender point with a length of about 0.55 the total length of the body. It is 

 subcouical anteriorly (about 55°), flaring widely at the base. According to Pouchet (18926), 

 the entire epieone is retractile and may almost completely disappear within the body. The 

 hypocone is long cylindrical or enlarged posteriorly. Its length on the dorsal side is about 0.78 

 of the total length of the body. 



The girdle is placed far anteriorly, its distance from the apex on the dorsal side being 0.18 

 of the total length of the body. Both ends turn posteriorly, meeting at a point slightly posterior 

 to the equator. The furrow is narrow, relatively .shallow, with overhanging borders. The sulcus 

 is not well defined in any of Pouchet 's (1885r7. 18926) figures. It apparently extends from the 

 girdle to the antapex. 



The nucleus is large and spheroidal, and is found near the center of the body. It is nearly 

 surrounded by a granular mass dark greenish brown in color, giving a dense ai)i)earance to the 

 central portion of the body. The remainder of the cytoplasm forms I'atliating strands extending 

 out from the central mass to the periphery, separated by vacuoles. Scattered through the 

 peripheral layer are granules green and brown like those surrouiuling the nucleus. Anteriorly 

 the cytoplasm has a yellow or-orange color. 



The most striking and at the same time puzzling fealun' of this organism is the seemingly 

 temporary or evanescent ju'otrusion which resembles a tentax^le. It is rather difficult to har- 

 monize the various figures of this species given by Pouchet (ISSaa, 18926) and his own description 

 does not clear up the difficulties. The girdle in figures 2 and 4, jilate 11 (18926), with its 

 posterior turn on the dorsal side, has no apparent relation to the same structure in figures 3 

 and 7 on the same plate, in which the girdle passes aci'oss the doi-sal side in a direction at right 

 angles to the long axis of the body. Variations to this extent in one species in the position of 

 the girdle are not known elsewhere in the Dinoflagcllata. The tentacle itself apparently arises 

 from the sulcal region near the posterior end of the body as a long, slender, protopla.smic extension 



