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('. H. OSTKMKI.I». 



other liaiul il is j)robal)k' Ihal C gracile Schult is the same species, 

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

 phores wilh my fig. 10, we will (ind a close resemblance; on the 

 contrary his ligures of resting spores diller from mine, bul 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 C gracile, but I 



Fig. 10. Chœtoceras gracile Schutt. ."jOO 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 secondar}' 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. ceratosporum 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. 



Anyhow the small solitary Chœtoceras species require a revision, 



