REPORT ON TUE DI ATOMACE.-E. 



119 



Stictodiscus japonicus, n. sp. (Plate I. fig. 2.) 



Granulorum lineis per plicas radiantes divisis prope marginem binatim oricntibus ; 

 areis mediis grandiusculis reticulatim dispositis singulo granulo plerumque distinctis. In 

 mari Japonico. 



This organism may be distinguished from the others by the circumstance that in it the 

 granules do not occur on the perimeter, while there are always two granules standing side 

 by side at the outer extremity of every row. The central areas are somewhat large, of 

 irregular forms, and are in most cases ornamented with a siugle granule. 



Stictodiscus affinis, n. sp. (Plate I. fig. 4.) 



Lineis granulorum per plicas circumradiantes divisis ; media superficies in areolas 

 reticulatim distincta; area? nonnullse granulo instructae. Ad Zebu in mari Philippinarum. 



This form is much akin to the preceding, but may be distinguished from it by the 

 fact that the lines of granules proceed from the margin — a peculiarity which may also 

 be seen in the variety described below. The two granules found at the outer ends of 

 every row in Stictodiscus japonicus do not occur here, where, moreover, the central 

 areas are of smaller sizes and somewhat more abundant. Although the majority of these 

 areas are ornamented by a single round granule, some of them are entirely devoid of this 

 structure, while others bear two. 



Stictodiscus affinis, n. sp., var. now (Plate I. fig. 6.) 



Differt a forma typica per lineas binis granulis ter vel quatuor vicibus repetitis 

 incipientes. Ad mare Philippinarum. 



In this Diatom the granule-bearing areas sometimes exhibit four pairs of puncta 

 towards the circumference of the disc. The central areas are somewhat irregular in size 

 and form, and while several are perfectly smooth others bear a single round granule. 

 Hence although not identical with the Zebu type, this frustule cannot be regarded as more 

 than a variety of it. 



Stictodiscus affinis, n. sp., var. latc-zonata, nov. (Plate XVII. fig. 11.) 



Although well characterised by its distinct granulated zone, this Diatom must be 

 viewed as a distinct variety of Stictodiscus affinis. It is principally distinguished by 

 the marginal radiating folds, which become reticulated towards the centre, and by the 

 distinct and regular lines of granules interposed between the folds. Marginally the 

 granular lines are ornamented by pairs of puncta placed laterally. Two well-defined 

 rings of approximately equal size run round the periphery. 



Stictodiscus affinis, n. sp., var. nov. (Plate XVII. fig. 8.) 



Another variety of the same species is here shown. The smallness of its disc and 

 the smaller number of its radii can certainly have no specific significance, but it may be 



