278 



С. H. Ostenfeld. 



other hand it is probable that С gracile Schutt is the same species, 

 because if we compare Schütt's figures of cells with chromato- 

 phores with my fig. 10, we will find a close resemblance; on the 

 contrary his figures of resting spores differ from mine, but he has 

 not drawn these spores in situ within cells, and it is perhaps per- 

 mitted to doubt, if they belong to the species in question. 



Paulsen (1. c.) has given figures from Østrup's original material 

 and considers his form as identical with Schütt's С gracile, but I 



Fig. 10. Chœtoceras gracile Schutt. 500 t. m. 



doubt if he is right in doing so. The question is a much intri- 

 cate one. 



The latest note by Apstein about these small solitary species 

 contains drawings of a species from the Baltic — the locality of 

 Schütt's species — which the author names C. gracile but, I think, 

 hardly correct; I myself know Apstein's form from the Belt Sea 

 (Baltic) and have found it with resting spores which differ consider- 

 ably from those of C. gracile; they have two rather large spines on 

 the primary spore-valve (in the same manner as the spores of C. 

 debile) and often also small spines, while the secondary valve is 

 smooth. The species has only one chromatophore, as also drawn 

 correctly by Apstein, and the corners of the cell in side view are 

 not contracted; all these distinctive marks separate it from the true 

 C. gracile, and I propose to name it C. ceratosporiim nov. sp.; it is 

 only known from the Baltic, where it occurs in the spring and 

 seems to have its true home in the inner part, as I have seen it in 

 samples kindly sent me by Dr. K. M. Levander of Helsingfors. 



Anj'how the small solitary Chœtoceras species require a revision, 



