4Q4 Mr. C. Mereschkowsky on Stauronella. 
LII.—On Stauronella, a new Genus of Diatoms. 
By C. MERESCHKOWSKY. 
[Plate VIIL.] 
Ir has been shown, in my paper “On Okedenia” *, what 
important results can be obtained if the study of diatoms is 
not cenfined to their dead shells alone, but if living specimens, 
and especially their endochrome, are also taken into considera- 
tion. It is there shown that a form generally thought to 
be a Navicula is not a Navicula at all, that a species referred 
to Amphora did not belong to that genus, and that both had to 
be united in a separate genus—Ckedenia; also how easy it 
was to distinguish some of the species of this genus on 
account of their endochrome, which otherwise could hardly 
be distinguished even as varieties. 
In the present note we have another example of the same 
kind. A diatom which is generally believed to belong to 
the genus Navicula, or to its section Stauroneis, proves, on 
account of its endochrome, not only not to belong to that 
genus, nor even to the family Naviculacez, but not to have 
any relation whatever to the whole tribe of the Naviculoid 
diatoms. 
The diatom to which I refer is the so-called Stauroneds 
constricta, EKhr. It was first introduced into science by 
Ehrenberg, who described it under that name in 1843 in his 
work on American Microgeology. But its appearance is so 
peculiar and so distinct from all other species of the same 
genus, especially when observed from the girdle-face, that it 
was soon removed from the genus Stawronets and placed by 
W. Smithy] in the genus Amphiprora, which this diatom, 
indeed, somewhat resembles in its girdle-face ; and most 
diatomists continued to name it Amphiprora constricta until 
a comparatively recent date. But this last genus was no 
more the right place for the diatom than the former one. 
At the time of W. Smith (1853-1856) Amphiprora was not 
well defined, and various heterogeneous forms have been 
united under this name; but since Rabenhorst, Pfitzer +, and 
especially Cleve have more strictly limited it to forms with 
a sigmoid raphe, Amphiprora constricta could no longer 
remain there, its raphe being straight and not sigmoid; 
* Supra, p. 415. : 
+ W. Smith, ‘Synopsis of the Brit. Diatomacez,’ 1853-1856, 
{ E. Pfitzer, ‘ Untersuchungen tiber Bau u. Entwicklung d. Bacillari- 
aceen, 1871. 
