3 o8 DISCOVERY REPORTS 



spines which are arranged spirally. Foramina sometimes rather large. Chromatophores : 

 numerous cocciform bodies. Diameter of valve 1 0-3011 ; pervalvar axis 20-4011. 



An oceanic species widely distributed in northern waters. It was observed occasion- 

 ally around the coast of South Africa, and in the Peru Current. 



Observed at Sts. 425, 427; WS 621, 709. 



Bacteriastrum hyalinum var. princeps (Castracane) Ikari. 



Ikari, 1927, p. 423, fig. 3. 



Hustedt, 1930, p. 615, fig. 355. 



Bacteriastrum varians, var. princeps Castracane, 1886, p. 84, pi. 14, fig. 2. 



Cells rectangular, cylindrical, united to form short chains. Valve surface furnished 

 with a circlet of usually sixteen to twenty-four bristles, which emerge and fuse with 

 those of the neighbouring cells close to the valve margin. At a distance of about one- 

 third of the total length of the bristles, bifurcation takes place. The bifurcate portions 

 are spirally twisted in the second half of their length, and usually lie in the same plane 

 as the chain axis. The bristles attached to the exterior valves of the terminal cells are 

 usually the same thickness as the others ; they are alike at both ends of the chain, and are 

 directed obliquely towards the chain axis, but only slightly so, and are not pendulous. 

 Foramina obscure, very narrow. Chromatophores: numerous cocciform bodies. 

 Diameter of valve 25-50/* ; pervalvar axis 44/1. 



A neritic species widely spread through tropical and subtropical seas. It was very 

 common around South Africa. 



Observed at Sts. 425, 427, 428, 435, 438, 439; WS 709, 710. 



Bacteriastrum varians Lauder. 



Lauder, 1864, p. 8, pi. 3, figs. 1-6. 

 Karsten, 1906, p. 170, pi. 34, fig. 1. 



Cells rectangular, cylindrical, united to form short chains. Valve surface furnished 

 with a circlet of usually six to ten bristles, which emerge and fuse with those of the 

 neighbouring cells close to the valve margin. The bristles remain fused for nearly half 

 their length and then furcate. The furcate portions lie in the valvar plane. The bristles 

 attached to the exterior valves of the terminal cells are usually thicker than the others ; 

 they bear spiral markings and are alike at both ends of the chain. They proceed outwards 

 at right angles to the chain axis, and their extremities are slightly curved and bent 

 slightly downwards towards the chain. Chromatophores: numerous cocciform bodies. 

 Diameter of valve 20-30/i ; pervalvar axis 24/t. 



An oceanic species, common in tropical waters. It was frequently observed around 

 the coast of South Africa. 



Observed at Sts. 425, 427, 428, 433 ; WS 706. 



