SYSTEMATIC ACCOUNT 285 



Ditylum sol (Grunow ex Van Heurck) De Toni. (PI. XII, fig. 4.) 



De Toni 1894, p. 1018. 



Hustedt, 1930, p. 787, fig. 460. 



Triceratium sol Grunow ex Van Heurck, 1881, p. 115. 



Cells triangular in valve view, rectangular in girdle view, usually solitary. Surface ot 

 valve undulate, differentiated into central and marginal areas. Central area finely 

 punctate, puncta in curved radiating lines. A small central hyaline area present. Hyaline 

 area surrounded by a few short blunt spines and having one long central spine. Marginal 

 areas covered with very fine puncta in more or less parallel lines. Margin of valve crenu- 

 late. Girdle usually simple, covered with extremely fine puncta. Chromatophores : 

 numerous cocciform bodies. Diameter of valve (length of side) 60-180/*; pervalvar 

 axis, excluding spine, 60-80/* ; length of central spine 60-76/*. 



A tropical form, probably oceanic. Occurs frequently in Atlantic Ocean, around the 

 Cape of Good Hope and in the China Seas. 



Observed at Sts. 425, 434, 440. 



Subfamily HEMIAULOIDEAE 



Genus Hemiaulus Ehrenberg 

 Ehrenberg, 18446 



Hemiaulus Hauckii Grunow ex Van Heurck. (PI. XII, fig. 14.) 



Van Heurck, 1880-5, P'- I0 3> %• I0 - 

 Karsten, 1906, p. 172, pi. 38, fig. 9. 

 Gran, 1905, p. 100, fig. 128. 

 Hustedt, 1930, p. 874, fig. 518. 

 Lebour, 1930, p. 183, fig. 143. 



Cells small, bipolar, sometimes solitary, but mostly united to form long chains, often 

 twisted. Valves elliptical, poles produced to form long thin processes. Processes straight, 

 slightly convergent, terminated by small spines. Surface of valve slightly concave, 

 valve mantle deep. The cells are very weakly siliceous and possess no visible structure. 

 Chromatophores : four to six small rounded bodies. 



A very common oceanic ? diatom, often found in dense masses. Seldom observed 

 north of 50 N. Very common in the Mediterranean, and off the east coast of Africa. 



Observed at Sts. 425, 440, 677, 679, 681, 1373. 



Subfamily EUCAMPIOIDEAE 



Genus Eucampia Ehrenberg 

 Ehrenberg, 1840 a 



Eucampia balaustium Castracane. (PI. XIII, figs. 8-10.) 



Castracane, 1886, p. 97, pi. 18, fig. 5. 



Karsten, 1905, p. 120, pi. 11, fig. 7. 



Molleria antarctica Castracane, 1886, p. 98, pl. 18, fig. 8. 



