REPORT ON THE DIATOMACE^E. 161 



The frustule is of moderate size, and bears radiating but interrupted lines of thinly 

 disposed granules. 



Coscinodiscus polyradiatus, n. sp. (Plate III. fig. 4.) 



Granulis sequalibus in lineis parallelis distributis, superficiem in pluribus triangularibus 

 dissepimentis dividentibus ; margine lato, striato. Ad mare Antarcticum. 



This elegant disc was collected in the Antarctic Ocean. It is divided by several 

 radiating lines into a number of triangular areas. These lines are made up of granules of 

 uniform size, and parallel rows of similar granules are disposed in the intermediate areas 

 until the whole of the central part of the disc is covered. This is inclosed by a large 

 striated border — a circumstance which especially distinguishes it from Coscinodiscus fasci- 

 culatus, A. S., 1 while a narrow peripheral margin bearing concentric rings is also present. 

 That this frustule constitutes a good species cannot be doubted. 



Coscinodiscus gemmatulus, n. sp. (Plate XVII. fig. 9.) 



E minimis ; margine lato, punctulato ; medio raris granulis vel margaritis in irregulares 

 et raros ordines radiatim dispositis. In mari Indico. 



This small but elegant disc is surrounded by a large striated and punctated marginal 

 belt. The centre is ornamented with sparsely disposed bines of rare granules which do 

 not reach the centre. 



Coscinodiscus cycloteres, n. sp. (Plate XXII. fig. 8.) 



E minimis; disciformis, valvis margine hyalino et zona granulata distinctis, a qua 

 aequaliuni granulorum linese procedunt, nonnullse ad centrum, alia3 plus minus breviores ; 

 linese centrales ab elevatiori granulo vel denticulo oriuntur. In mari glaciali Antarctico. 



This elegant small disc possesses a hyaline margin within which a densely granulated 

 belt runs round the valve. From this belt a series of granulated lines proceed towards 

 the centre, and of these a few almost reach that point, while the others are shorter and of 

 different lengths. The lines which pass almost to the centre originate at the inner border 

 of the hyaline margin in somewhat salient granules or denticules. 



Coscinodiscus (?) polygonus, n. sp. (Plate XXII. fig. 6.) 



Valvis polygonis finissime striolatis; superficies plurimis denticulorum lineis irregu- 

 lariter distributis et interruptis ornata. Ut supra. 



Among the collections made in the Antarctic Ocean polygonal discs fringed by a very 

 delicate dentation are not unfrequently met with. The surface of the valve in the present 

 case is ornamented by numerous radiating lines of small points or denticules — the lines 



! * Compare A. Schmidt's Atlas, pL lvii. figs. 9 and 10. 

 (bot. chall. exp. — part iv. — 1886.) D 21 



