35o DISCOVERY REPORTS 



Genus Tropidoneis Cleve 

 Cleve, 1 89 1 



Tropidoneis antarctica (Grunow) Cleve. 



Cleve, 1894, p. 24. 



Karsten, 1905, p. 128, pi. 18, fig. 7. 



Cells large, somewhat weakly siliceous. Valves elliptical in outline, not furnished with 

 wings. Median line straight, very thin, dilated to form a small central area in the shape 

 of a narrow stauros. Valve furnished with very fine transverse and longitudinal striae. 

 The transverse striae are a little more prominent than the longitudinal ones. Connective 

 zone simple, cell rectangular in girdle view. Chromatophores : two plates. Apical axis 

 of cell 1 00- 1 50/1. 



Probably oceanic. 



Observed at Sts. 302, 452, 453, 463, 666. 



Tropidoneis belgicae (H. van Heurck) Heiden et Kolbe. 



Heiden and Kolbe, 1928, p. 655, pi. 4, fig. 98. 



Amphiprora belgicae H. van Heurck, 1909, p. 14, pi. 1, fig. 15. 



Cells weakly siliceous. Valves convex, outline undulate, constricted slightly at the 

 middle, apices broadly rounded, slightly capitate. Raphe very fine, straight, polar 

 nodules distinct, central nodules less distinct. Valve surface furnished with very fine 

 striation somewhat divergent at the apices, but transverse throughout the greater part 

 of the valve surface. Connective zone strongly developed, complex. Apical axis of cell 

 80/x, transapical axis 20/x. 



This characteristic form was observed but only in small numbers from water obtained 

 from melted ice. 



Observed near St. 560. 



Tropidoneis proteus Karsten. 



Karsten, 1907, p. 398, pi. 47, fig. 1. 



Cells solitary, valves elliptic-lanceolate in outline, apices acute. Valve surface un- 

 dulatory. Central knot rudimentary, raphe straight, faint, usually accompanied by two 

 parallel lines. Valve covered with very fine striation. Cells in girdle view exhibit a cer- 

 tain amount of characteristic torsion, connective zone simple. Chromatophores: 

 numerous thin bands, or vermiform bodies which radiate from a prominent central 

 nucleus. Apical axis of cell 1 50-1 70^; transapical axis 40-50/x. 



This rather weakly siliceous form occurred but rarely at one station to the south of 

 Africa. It is probably neritic. 



Observed at St. 440. 



