REPORT ON TTIE DIATOMACKffl. 143 



Actinocyclus clevei, n. sp. (Plate IV. fig. 6.) 



E maximis ; dense et decussatim punctulatis ; centrum sex cellulis oblongis dis- 

 tinguitur, a quo dupliccs perspicuorum punctulorum linea? dimanant, superficiem in partes 

 aequales dividentes ; pseudo-nodulo intramarginali grandiusculo. Diametrum 360 n. 

 In mari interno Japonico. 



This disc has a diameter of 360 m, and the great delicacy of its punctation contrasts 

 distinctly with its unusually large size. A central rosette is constituted by a few large 

 irregular oblong cellules, and from this region numerous double lines of more salient points 

 radiate outwards and terminate at the circumference, while the equal interspaces are orna- 

 mented by very minute puncta arranged in a decussate manner. The submarginal 

 pseudo-nodule is rather large, and is somewhat elevated above the surface in a subulate 

 manner. The specimen figured was collected in the Sea of Japan. 



The specific name has been given in honour of the well-known diatomist Professor 

 Cleve of Upsala. 



Actinocyclus japonicus, n. sp. (Plate IV. fig. 3.) 



E maximis ; valvis fasciculatim punctulatis ; fasciculi punctulati lineis radiantibus dis- 

 septi quae in denticulo desinunt ; punctuli circum in zonam decussatim dispositi ; pseudo- 

 nodulum submarginale grandiusculum. Ad oras Japonicas. 



This magnificent discoid form is not smaller than Actinocyclus clevei, but differs not- 

 ably from the latter in all its remaining characteristics. The puncta, which are dissemi- 

 nated over the valve, are less delicate and more sparsely disposed, and at the centre there 

 exists a group of small points in the middle of an irregular hyaline area. A series of 

 radiating punctated lines divide the surface of the valve into a number of equal segments, 

 which are sculptured by rows of fasciculated granules that are arranged in quincuncial 

 order near the circumference. The radiating lines terminate in submarginally placed denti- 

 cules, and the external limiting circlet is ornamented by well-defined striae. The Diatom 

 was found in the vicinity of the coast of Japan. 



Actinocyclus ralfsii, W. Sm., var. challengerensis, nov. (Plate XXX. fig. 1.) 



The frustule here shown was also collected in the neighbourhood of Japan. Although 

 in the course of engraving the striae have been somewhat unduly reduced in number, it is 

 manifest that it closely resembles the Actinocyclus ralfsii of '. W. Smith. It may be noted, 

 however, that the marginal denticules are more pronounced than in the latter case, while 

 the system of striae is fasciculate rather than radiating. Notwithstanding these distinc- 

 tions, it can only be looked upon as a variety of Smith's species. 



