SYSTEMATIC ACCOUNT 261 



of larger puncta arranged in concentric lines ; puncta decussate, beyond which is an 

 outer or marginal band which is radially striate. A ring of stout spines decorates the 

 inner marginal band of puncta. A prominent pseudo-ocellus is situated just inside the 

 inner marginal band, pseudo-ocellus circular. Diameter of valve 100-140/x. 



The type of the species was collected in the Sea of Japan. This species has been re- 

 corded from numerous localities in the northern hemisphere, particularly from the 

 coasts of China and Japan, but has not been previously recorded from the Antarctic. 



Observed at St. 50 5. 



Actinocyclus corona Karsten. 



Karsten, 1905, p. 92, pi. 9, fig. 6. 



Cells discoid, solitary, small, valves similar. Valves convex, slightly flattened towards 

 the centre.- Valve covered with granules in radial lines; puncta somewhat indistinct in 

 the central area, more prominent in the peripheral area. A corona of very prominent 

 and slightly larger puncta occurs at a distance equal to about half the radius. This 

 corona usually occupies three or four concentric lines of puncta. The valve is sur- 

 rounded with a narrow hyaline margin. Pseudo-ocellus small, marginal. Diameter of 

 valve 40/x. 



A small neritic species, seldom occurring in large numbers. 



Observed at St. 453. 



Actinocyclus elegans Karsten. 

 Karsten, 1905, p. 93, pi. 9, fig. 9. 



Cells discoid, solitary, small. Valves convex, often deeply so, surrounded by a broad 

 flattened margin. Central area of valve flattened, sometimes slightly depressed, and 

 furnished with a distinct rosette of eight to ten cells. The remainder of the valve surface 

 is covered with hexagonal areolation decreasing in size as it proceeds to the margin. 

 Four darker lines radiating from the central rosette divide the valve into equal parts. 

 These lines are sometimes distinct over their entire length, but may be obscure in 

 places, or entirely absent. Margin flat, inner zone faintly punctate, outer zone hyaline. 

 A small rounded pseudo-ocellus present, situated upon the outer hyaline zone. Diameter 

 of valve 50-64/x. 



A small neritic species, probably a bottom form. 



Observed at St. 666. 



Actinocyclus intermittens Karsten. 

 Karsten, 1905, p. 92, pi. 9, fig. 5. 



Cells discoid. Valves convex, slightly flattened towards the centre. Valves covered 

 with puncta, somewhat irregularly arranged towards the centre, but in radial lines in the 

 peripheral area. Valve surrounded with a narrow hyaline margin, furnished with a small 

 pseudo-ocellus. Diameter of valve 64^. 



Neritic, widely distributed in the Southern Ocean, but seldom found in numbers. 



Observed at Sts. 384, 461, 477, 543, 544, 551, 570; WS 548, 549, 550. 



