3°o DISCOVERY REPORTS 



Cells united to form long chains. Valves elliptical in outline, surface concave ; angles 

 produced slightly, somewhat truncate, firmly abutting those of the neighbouring cells. 

 Bristles rather thin, emerging from the angles, obliquely, weakly curved, slightly 

 divergent. The lower valve of a terminal cell is differentiated. The valve surface is 

 slightly convex, and the bristles are large and thick. The bristles emerge from the angles 

 of the valve obliquely ; they are somewhat curved, diverging until in a position almost 

 at right angles to the axis of the chain, where they are bent suddenly towards the chain 

 axis, and, converging slightly, their extremities are again bent in a direction parallel with 

 the axis of the chain. These terminal bristles are somewhat flattened, and bear a few 

 extremely fine spines. Foramina oval-elliptical. Chromatophores : numerous short 

 vermiform bodies. Diameter of valve 40 /x. 



An oceanic species, common in the Indian Ocean. It was observed occasionally 

 around the coast of South Africa. 



Observed at Sts. 425, 427, 428, 438. 



Chaetoceros capense Karsten. 



Karsten, 1906, p. 167, pi. 31, fig. 7. 



Cells small, united to form chains, four to eight cells in a chain. Valve elliptical in 

 outline, valve surface concave, angles produced to form long thin bristles. Valve mantle 

 deep, sharply constricted as it joins the connective zone. Girdle also deep, pervalvar 

 axis usually twice the apical axis. Foramina broadly elliptical. Chromatophores : four 

 irregular plates. Diameter of valve 10-18/^ ; pervalvar axis 34^. 



A small oceanic species, common around the coast of South Africa. 



Observed at Sts. 431, 434, 435, 436, 437, 438. 



Section Compressa 



Chaetoceros compressum Lauder. 



Lauder, 1864, p. 78, pi. 8, fig. 6. 

 Hustedt, 1930, p. 684, fig. 388. 

 Lebour, 1930, p. 132, fig. 96. 



Cells united to form short chains, often twisted. Valves oval-elliptical to circular, 

 valve surface flat or slightly convex. Cells in girdle view rectangular, often almost 

 square. Bristles emanating from the valve surface close to the margin of the valve, 

 bristles thin and often straight; occasionally bristles are noticed which are much 

 stronger and thicker than the others, they are wavy and bear short spines, and are bent 

 back towards the axis of the chain. Foramina usually small, narrow. Chromatophores: 

 numerous small rounded bodies. Diameter of valve 20-30/1. 



Usually regarded as a boreal species, having a wide distribution in northern European 

 waters. It was observed in small numbers off the coast of Africa. 



Observed at Sts. 383, 427, 428, 434, 1356, 1358. 



