294 DISCOVERY REPORTS 



Chaetoceros danicum Cleve. 



Cleve, 1889, p. 55. 



Lebour, 1930, p. 124, fig. 89. 



Cells usually solitary, but sometimes in short chains of three to eight cells. Valve sur- 

 face flat, oval in outline. Valve mantle deep, bristles thin, almost straight, emanating 

 from the margin of the valve, perpendicular to the pervalvar axis. The bristles of the 

 upper valve are often almost at right angles to those of the lower valve. Foramina much 

 reduced, almost absent. Chromatophores : numerous cocciform bodies, nucleus seldom 

 central. Diameter of valve 16-20^. 



A small neritic species having a very wide distribution. Common in European waters 

 and in the Atlantic and Indian Oceans. Observed at one station only off the coast of 

 Africa. 



Observed at St. 1373. 



Chaetoceros aequatoriale Cleve. 



Cleve, 1873 «, p. 10, pi. 2, fig. 9. 

 Karsten, 1907, p. 389, pi. 45, fig. 1. 



Cells usually solitary, rectangular in girdle view, with rounded angles. Valves almost 

 circular in outline, with a slightly convex surface, rounded at the margin. Valve mantles 

 sharply constricted immediately above the girdle, girdle narrow. Bristles long, very 

 strong, emerging almost from the centre of the valve, proceeding outwards almost at 

 right angles to the pervalvar axis, then sweeping downwards in shapely curves con- 

 verging towards their extremities. The bristles of the upper valve almost parallel with 

 those of the lower throughout the entire length. The bristles are thick at the point of 

 emergence, tapering gently. They are marked with longitudinal ridges and transverse 

 striation, are somewhat angular in cross section, and armed with small spines throughout 

 their entire length. Chromatophores: numerous rounded bodies. Diameter of 

 valve 25 p. 



An oceanic species, widely spread throughout the Indian Ocean. It was observed 

 frequently around South Africa and to the south of Madagascar. 



Observed at Sts. 425, 427, 433, 435, 440, 1570, 1572, 1574. 



Chaetoceros curvatum Castracane. 



Castracane, 1886, p. 77. 

 Mangin, 1915, p. 36, figs. 15, 16. 



Cells usually solitary, but sometimes united in short chains of two to six cells. Valves 

 dissimilar. Valve surface elliptical to circular in outline, the upper convex, the lower 

 either flat or concave. The valve mantle of the upper valve greater than that of the lower. 

 Bristles usually short and somewhat tortuous, particularly those on the lower valve. The 

 bristles emerge from the centre of the upper valve, and are bent so as to hang in a more 

 or less pendulous fashion almost parallel with the bristles of the lower valve, which also 

 emerge from the centre of the valve. The bristles of the upper valve originate as two 



