SYSTEMATIC ACCOUNT 253 



or less the same size at all points over the valve surface. Girdle simple. Marginal 

 spinulae absent. Chromatophores : few rounded bodies. Diameter of valve 70-90/x, 

 mostly 86/m. 



Observed at St. 666. 

 Coscinodiscus inflatus Karsten. 

 Karsten, 1905, p. 85, pi. 7, fig. 7. 



Cells discoid, solitary. Valves flat or nearly so. Valves covered with fine puncta 

 arranged in fascicules of parallel lines ; no central hyaline area. Margin furnished with 

 usually five elongated marks, radially disposed. Puncta at the central area somewhat in- 

 distinct, but, generally speaking, the same size over all the valve surface. Chromato- 

 phores: few rounded bodies. Diameter of valve 90-160/u., mostly 120/i. 



This diatom, which is typically Antarctic, occurred in small numbers at one station 

 only, off South Georgia. The specimens were consistently larger than those described 

 by Karsten. 



Observed at St. 475. 



Coscinodiscus kryophilus Grunow. 



Grunovv, 1884, p. 81, pi. 3, fig. 21. 

 Karsten, 1905, p. 85, pi. 7, fig. 4. 



Cells discoid, small, valves convex, strong. Valves covered with fine parallel lines of 

 puncta ; lines not closely packed, arranged in radiating fascicules. Punctation entire, no 

 central hyaline area. Puncta uniform in size over the whole of the valve surface. Margin 

 of valve furnished with a number of small but clearly marked spinulae. Chromato- 

 phores: numerous irregularly stellate or lobed bodies. Diameter of valve 40-447* . 



A few specimens only were observed at one station on the 30th W. meridian, in the 

 South Atlantic. The exact distribution of the species is unknown. It was recorded from 

 the Arctic Seas by Grunow, but is never found in great numbers. The specimens 

 observed were remarkably constant in size, and failed to attain the maximum diameter 

 given by Karsten (ioo/i). The species resembles C. incurvus Karsten, but is generally 

 much smaller, and more robust. The striae of the latter are more densely arranged than 

 in Grunow 's species. 



Observed at Sts. 301, 302, 666. 



Coscinodiscus pyrenoidophorus Karsten. 

 Karsten, 1905, p. 84, pi. 5, fig. 11. 



Cells discoid, solitary, small. Valves flat or nearly so. Valves covered with lines of 

 puncta arranged in fascicules, with striae parallel to the middle radius of each fascicule. 

 Central hyaline area present, small. Margin of valve devoid of structure, having the 

 appearance of a plain hyaline peripheral area; spinulae absent. Chromatophores: a 

 number of irregular plate-like bodies. Diameter of valve, 60-74/M, mostly 70/x. 



A neritic species observed off the coast of South Georgia, never found in great 

 numbers. 



Observed at Sts. 335, 336, 337, 338, 666. 



