SYSTEMATIC ACCOUNT 335 



Synedra pelagica Hendey, nom.nov. 



Synedra spathulata Schimper ex Karsten, 1905, p. 124, pi. 17, fig. 11. 

 non Synedra spathulata O'Meara, 1875, p. 310, pi. 28, fig. 34. 



Cells very long and narrow, hair-like, often matted together in dense masses. Cells 

 slightly inflated towards the centre and at the ends, but not abruptly so. Cells often 

 curved, sigmoid, or twisted. Valve surface bears very faint short striae, often seen only 

 upon the terminal inflations. Chromatophores : numerous elongated bodies scattered 

 throughout the whole length of the cell. Apical axis of cell 800-2400^, transapical axis 

 5-9^. Type locality Antarctic Ocean. 



This organism is often found in enormous quantities in the Southern Ocean and 

 was described by Karsten (1905) as appearing in Schimper 's note-book as Synedra 

 spathulata, n.sp. This name, however, was preoccupied (O'Meara, 1875). The new 

 name Synedra pelagica is used to describe the form mentioned by Schimper (in MSS.) 

 and by Hart (1934, p. 167). 



Observed at Sts. 432, 577, 666, 671, 673 ; WS 666. 



Synedra stricta Karsten. 



Karsten, 1906, p. 173, pi. 30, fig. 19. 



Cells very long and narrow, straight, often in dense masses. Valves of uniform dia- 

 meter throughout the whole length, no median or terminal inflations. Apices rounded, 

 not spatulate or bulbous. Valve furnished with a prominent pseudoraphe, and 

 numerous fine short transverse striae. Chromatophores: numerous rounded or rod- 

 shaped bodies. Apical axis of cell 750-2000^, transapical axis 6-8 \x. Type locality, 

 Port Elizabeth. 



Probably a neritic species, common around South Africa. 



Observed at Sts. 434, 435, 436, 438, 439. 



Genus Thalassiothrix Cleve et Grunow 

 Cleve et Grunow, 1880 



Thalassiothrix acuta Karsten. 



Karsten, 1906, p. 173, pi. 30, fig. 20. 



Cells very long and thin, forming long tangled masses. The cell shows often a certain 

 amount of torsion about the apical axis, but seldom sigmoid as in many similar forms. 

 Apices attenuate. Valve furnished with a narrow and indistinct pseudoraphe, and fine 

 transverse striae. Chromatophores: numerous small rounded bodies. Apical axis 

 1-2 mm. ; transapical axis 4-6/x. 



Observed at Sts. 434, 435, 437, 438, 439; WS 481, 646. 



Thalassiothrix antarctica Karsten. 



Karsten, 1905, p. 124, pi. 17, fig. 12. 

 Skvortzovv, 193 1 a, p. 80, pi. 2, fig. 5. 



D XVI 24 



