KOFOID AND SWEZY: UNARMORED DINOPLAGELLATA 307 



Comparisons. — The small yellow-oclire spherule found in this species is 

 probablv pigment similar to that present in G. ochraccum (pi. 7, fig. 76). It 

 did not show the same motility, Init contiimed oljser\-ation may establish its 

 similarity in that respect also. It differs from G. ochraceum in its type of 

 surface striae and in the smaller degree of torsion of the sulcus, with 0.1 as 

 compared Avith 0.5 turns aliout the body. This species has the most highly 

 developed apical point in the genus except for those of G. fusifonne nom. sp. 

 nov. and G. lacliryma (Mevmier). 



G-yrodinium fusiforme nom. sp. nov. 

 Text figures EE, 4, 8 



Spirodinium fusus Meunier (1010), p. 63, pi. 14, figs. 23-26. 



Not Gyrodiniiim falcatum nom. sp. nov. {= Gymnodinium fusus Sehlitt (1895) in part). 



Diagnosis. — A small species with slender fusiform body, its length 3.7 trans- 

 diameters; girdle a descending left spiral, displaced 1.4 trausdiameters ; sulcus 

 not determined. Length, 74/^. Arctic Ocean. 



Descrdptiox. — The body is slender fusiform, tapering to a sharp point at both apices, widest 

 in the middle, its length 3.7 trausdiameters at the widest part. The epicone and hypocone are 

 subequal. The epicone is slender conical, about 30° anteriorly, .slightly broader posteriorly, with 

 a slender, acuminate apex. It has a length on the left and right sides of 0.29 and 0.71 respectively 

 of the total length of tlie body. The hypocone is also slender conical, with a long attenuate 

 antapex in the type figure (fig. EE, 4), somewhat shorter and blunter in a second specimen 

 (fig. EE, 8). 



The girdle is a descending left spiral with a distance from the apex at its proximal and distal 

 ends of 0.29 and 0.71 trausdiameters respectively. The furrow is not distinctly marked off in 

 ]\Ieunier's figures, but it seems to have a width of about 0.18 transdiameter, and is shallow with 

 rounded borders. The sulcus is imperfectly represented in the figures. 



The nucleus is an ellip.soidal body filled with moniliform chromatin strands and lying in the 

 central or anterior part of the body. Its major and minor axes are 0.8 and 0.5 trausdiameters 

 respectively. 



Immediately posterior to the nucleus is a large vacuole. The peripheral zone of cytoplasm is 

 filled with short rodlets apparently arranged at right angles to the surface. 



Dimensions. — Length, 74^ ; transdiameter, 20/^ ; axes of nucleus, 16m and 10^. 



OcctTBRENCE. — This species was figured by Meunier (1910) from material 

 collected by the Duke of Orleans's Arctic Expedition of 1907 in the Arctic 

 Ocean near Nova Zembla. 



Synonymy. — iNleunier (1910) described his species as Spirodinium fusus. 

 This name was preoccupied by Gijiiinodinium fusus Schiitt (1895), imder which 

 designation two different forms were figured, one a Gymnodinium, G. fusus 

 Schiitt, and the other a Gijrodiiiium, G. falcaluni nom. sp. nov.. which we have 

 separated from Schiitt 's species. We therefore cliange the specific name of 

 Meunier's form to fusiforme, on the ground that the specific name fusus was 

 once applied to a species which is now im-ludcd within Gyrodinium (now G. 

 falcatum). 



