SYSTEMATIC ACCOUNT 349 



Pleurosigma Smithianum Castracane 

 Castracane, 1886, p. 38, pi. 28, fig. 6. 



Valves strongly sigmoid, somewhat broad, apices acute. Raphe strong, very promi- 

 nent, following closely, and in some cases almost concurrent with the dorsal flexures of 

 the valve margin. Central nodule small, surrounded with a small oval central area. 

 Striation very faint, consisting of transapical lines at right angles to the polar axis of the 

 cell. Apical axis of cell 140/i. 



Castracane 's illustration does not show the striation, nor is any mention made of it in 

 his description ; but from herbarium specimens I have examined, which came from the 

 same locality as Castracane's type, I was able to satisfy myself that specimens corre- 

 sponding to the shape and characters of Castracane's species obtained from the same 

 locality, were furnished with striation at right angles to the polar axis of the valve, and 

 not oblique striation. Consequently I have used Castracane's name to describe the 

 specimens from the Bransfield Strait. 



Observed at St. WS481. 



Subfamily AMPHIPROROIDEAE 



Genus Amphiprora Ehrenberg 

 Ehrenberg, 1843 



Amphiprora Kjellmanii Cleve. 



Cleve and Grunow, 1880, p. 15, pi. 4, fig. 83. 

 Meunier, 1910, p. 291, pi. 32, figs. 4, 6, 7. 



Cells large, solitary, tortuous about the valvar axis. Valves elliptic-lanceolate, apices 

 rounded, with a prominent keel. Valves furnished with wing-like projections. Alae 

 sigmoid, striate, striae well marked. Connective zone complex, consisting of a number of 

 folds. Apical axis of cell 130/u ; transapical axis 40/x. Type locality, Kara Sea. 



This species is found, but never in great numbers, in the Arctic Seas, and has not 

 been reported previously from the Antarctic. A few isolated specimens were observed 

 off South Africa. 



Observed at St. 440. 



Amphiprora Oestrupii Van Heurck. 

 Van Heurck, 1909, p. 15, pi. 1, fig. 22. 



Cells solitary, oblong in outline with a slight constriction close to the central nodule ; 

 angles rounded. Median hyaline area extended to the connective zone. Alae well de- 

 veloped, transversely striate ; striae parallel in the median area, but curved towards the 

 apices of the cell. Connective zone composed of numerous plicae. Apical axis of cell 

 1 60/x . 



This species was observed only in small numbers from water obtained from melted 

 ice. 



Observed near St. 560. 



