SYSTEMATIC ACCOUNT 313 



Gran, 1905, p. 54, fig. 66. 

 Hustedt, 1929, p. 592, fig. 339. 

 Lebour, 1930, p. 99, fig. 72. 



Cells cylindrical, tubular, with regularly conical valves, terminated with a curved 

 spine. Spine slightly eccentric, producing a faint depression on the neighbouring cell at 

 the place of attachment. Connective zone furnished with lines of intercalary scale-like 

 markings. In small specimens the scales are arranged in two dorsiventral lines, but in 

 the larger ones seven to ten lines may be present, giving the zone a squamose appearance. 

 The connective zone is very minutely punctate. The whole cell is weakly siliceous, and 

 the markings in the zonal aspect are seen with great difficulty even when the specimens 

 are examined mounted dry. Chromatophores : a few rounded bodies. Diameter of cells 

 20-80^ ; pervalvar axis 700/^. 



An oceanic species common in tropical seas, very common in the Mediterranean, but 

 seldom observed in the North Sea. It was observed frequently around the coast of 

 Africa, particularly upon the eastern side, and also in the material from the Pacific taken 

 in the Peru Current. 



Observed at Sts. 425, 427, 428, 437, 439, 1373 ; WS 709, 710. 



Rhizosolenia Castracani H. Peragallo. 



Peragallo, H., 1888, p. 83, pi. 6, fig. 42. 

 Karsten, 1906, p. 164, pi. 30, fig. 144. 

 Hustedt, 1929, p. 607, fig. 351.. 

 Lebour, 1930, p. 103, fig. 75 a. 



Cells large, cylindrical, furnished with small conical valves. Apex of the valve short, 

 oblique, terminated with a very small spine, basis of spine often inflated. Connective 

 zone furnished with numerous pervalvar lines of intercalary scale-like markings. Scales 

 somewhat irregular as they approach the valve. The cell wall is rather thick and strong, 

 but the imbricate markings are seen with difficulty. The connective zone is punctate. 

 Chromatophores: several rounded bodies. Diameter of cells 150 -180/* ; pervalvar axis 

 600-750/Li. 



An oceanic species common in temperate waters. It is found frequently in the 

 Atlantic Ocean and in the Mediterranean. It was observed off the coast of South Africa 

 and off the Cape Verde Islands. 



Observed at Sts. 434, 438, 684. 



Rhizosolenia Chunii Karsten. 



Karsten, 1905, p. 99, pi. 11, fig. 5. 

 Cells cylindrical, forming short chains, sometimes slightly flattened laterally. Cells 

 straight, almost rectangular. Valves slightly convex, but sometimes almost flat, fur- 

 nished with a short sharp spine placed in a marginal position. Spines hollow at base, 

 difficult to see, except those which project beyond the terminal valves. Connective zone 

 composed of two lateral lines of intercalary scale-like markings in zigzag rows. Scales 



