Mr. C. Mercschkowsky on Scllaphoi-a. 185 



XXX. — On Sellaphora, a new Genus of Diatoms. 

 By C. Mereschkowsky. 



[Plate IV.] 



The method of stiuly'my diatoms exclusivtdy on dead sliells, 

 wliieli has, with few exeeptions, been the practice since tliesc 

 little alga- first became known, will soon, I believe, have to be 

 rei)laced by a broader and more scientific process, based not 

 only on characteristics of valves and frustides, but also on 

 those of the inner structure ; and tliis will no doubt result in 

 great ciianges in the whole science of diatomology. New 

 genera, based on cell-contents, will be founded, new groups 

 established, and the afiinities of the diatoms will prove to 

 be very different from what is now supposed to be true. 



This conviction is the result of long and careful studies of 

 living diatoms in which 1 have been engaged for the last few 

 years, and which have given many unexpected results. Some 

 of these results have already been described in my previous 

 papers *, and it is my intention to discuss them more fully 

 in an extensive work on the inner organization of diatoms 

 which I am now preparing. 



In the present note I shall give the description of a few 

 interesting forms which I have recently found abundantly in 

 California. They are a good illustration of the great import- 

 ance of the inner structure in dealing with diatoms. Any 

 diatomist would certainly place them in the genus Navicula 

 if dead shells alone were known, and, in fact, one of these 

 forms has always been regarded as a Navicula. But if their 

 inner structure, and especially the endochrome, is taken into 

 account, it becomes evident that they do not belong to that 

 genus, their endochrome being very different from that of 

 Navicula or any other allied genus. They represent no doubt 

 a new genus. 



One of these forms is the well-known Navicula pupula 

 Kiitz., not uncommon in fresh water; the other two are new 

 species, also not rarely to be met in salt water. The latter 

 are small delicate forms of which I have not yet mounted 

 specimens, so that the structure of the valves cannot be 



miire sur la Structure interieure des Diatomees," Scripta liotunica St 

 I'ctcr.-burtr, fat^c. xix. (1902 j. 



