SYSTEMATIC ACCOUNT 303 



bristles upon the lower valve of a terminal cell are very much stouter than the others. 

 They emerge from the angles of the valve and proceed outwards obliquely. At ap- 

 proximately two-thirds of the length, the bristles are bent and proceed in a direction 

 almost parallel with the axis of the chain. These terminal bristles widen considerably at 

 the place of bending but taper to a fine hair-like extremity, also they are armed with fine 

 spines through the greater part of their length. They closely resemble the terminal 

 bristles of C. buceros Karsten, and are somewhat tortuous. Foramina narrow, linear 

 lanceolate. Chromatophore : one large plate. 



Probably a neritic species, favouring a high salinity and warm water. It was observed 

 frequently but never in great numbers along the east coast of Africa and at one station 

 only in the Peru Current. 



Observed at Sts. 425, 1356, 1358, 1359, 1584, 1586; WS 710. 



Section Furcellata 



Chaetoceros neglectum Karsten. 



Karsten, 1905, p. 119, pi. 16, fig. 5. 

 Mangin, 1915, p. 47, fig. 29. 



Cells small, united to form chains, chains sometimes twisted. Cells in girdle view 

 rectangular or suboctagonal, weakly siliceous. Valves flat at the centre, valve mantle 

 narrow, sloping obliquely to the connective zone. Bristles very fine, emerging just inside 

 the flattened portion of the valve surface and proceeding in a direction parallel with the 

 axis of the chain to meet those of the neighbouring cell when they turn outwards im- 

 mediately at right angles to the axis of the chain. Bristles smooth. Foramina rect- 

 angular. Chromatophore: one plate lying close to the girdle. Diameter of valve 10-15/*. 



A small characteristic Antarctic diatom common on the western side of the Southern 

 Ocean. It was observed, sometimes in great numbers, around the South Shetlands, 

 South Georgia, the South Sandwich Group and again far south in the Weddell Sea and 

 the Bellingshausen Sea. It is probably neritic and favours a low salinity. 



Observed at Sts. 337, 338, 378, 379, 380, 382, 383, 434, 435, 436, 437, 438, 439, 

 475> 477. 478, 479. 481, 5 OI > 5 o6 - 5 o8 > 5 IO > 5^, 5^ 575- 576, 577, 578, 580; WS 100, 

 548, 549- 55°- 55 1 - 552A, 598. 



Chaetoceros filiferum Karsten. 



Karsten, 1907, p. 392, pi. 44, fig. 5. 



Cells united to form short chains, four to twelve cells in a chain, cells rectangular in 

 girdle view. Valves almost circular in outline, with a flat or slightly convex surface. 

 Bristles emerging from the angles of the cells and crossing those of the neighbouring 

 cells outside the girdle line. Bristles short, slightly curved, smooth. Foramina elong- 

 ated, narrow. Chromatophores : two in each cell. Diameter of valve 20-24/x. 



Probably an oceanic species, observed in small numbers in the Indian Ocean and off 

 the coast of South Africa. 



Observed at St. 425. 



