JANISCHIA. 



537 



The genus Janischia only comprises one species, J r . antiqua. Grim. 

 (Cosd?iodiscus Ludovidanus Rait.), fig. 282, (H.V.H. Atl., pi. 95 bis, f. 10, 11). 

 This is in reality a very peculiar Cosdnodiscus, the structure of which closely 

 resembles Brunia, but with this difference, that in the Janischia the peculiar 

 band does not make a complete circuit of the valve, and has only a very 

 slight development in breadth. 



StOSchia Janisch (in litteris) is a reniform Cosdnodiscus, which Mr. 

 Rattray has described under the name of C. reniformis. It is represented in 

 the text (fig. 283). Is it a constant form or only a deformed valve? I am 



Fig. 283. Stoschia. 



if 



unable to answer this question. Mr. Janisch 

 certainly examined this curious diatom in his work 

 on the Expedition of the Gazelle. Numerous 

 examples of this interesting form have been found 

 on the West Coast of Africa. 



Willemoesia Castr., 1886, is also 



described by Mr. Rattray as a Cosdnodiscus. I 

 give in the text (fig. 284) after Castracane a figure 

 of Willemoesia humilis Castr. {Cosdnodiscus humilis 

 Rattr.), which has been found in one ol the 

 gatherings of the Challenger Expedition. Its 

 habitat is unknown. 



Fig. 284. Willemoesia 

 humilis. 



