Mr. C. Mereschkowsky on Stauronella. 425 
and so it was again removed to the Naviculacee, and placed 
by Cleve * in the genus Navicula, section Microstigmatice, 
division or subgenus Stauronets, under which name it has 
also recently been described by Peragallo fT. 
It can, however, be easily shown that this is not its proper 
place, that it has no real affinity to the Naviculacez, and that 
therefore this unfortunate diatom has again to be removed 
somewhere else. But since it cannot find a suitable home in 
any of the existing genera, it clearly results that it has to 
seek one elsewhere—in other words, it ought to form a new 
genus, which | propose to call Stauronella; and by so doing 
I hope all trouble with this unfortunate diatom will cease, and 
it will find in the new genus a well-merited rest. 
As I intend to prove the necessity of constituting this new 
genus on account of its endochrome, we will now proceed 
to the description of the latter. It is, however, not on the 
type species that we will study the endochrome, but on anew 
variety (var. linearts, Mer.), the description of which will be 
given below. 
The endochrome is composed of two plates, which are 
characterized by a very peculiar disposition, not to be found 
in any other species of Naviculoid { diatoms. Each half of 
the frustule, the superior and inferior, has its own plate, both 
being separated in the central part of the frustule by a trans- 
verse hyaline space, z. e. by an interval directed along the 
shorter axis; both plates rest by their median part on one 
of the connecting-zones (fig. 19), which might be called 
the dorsal connecting-zone. The margins of the plates 
rest on the surface of both valves, covering their whole 
breadth (figs. 16, 17, 19). When seen from the girdle- 
face these margins appear as dark lateral bands on both 
sides of the frustule (fig. 18, c); the lighter part, uniting 
them, corresponds to the median portion, which, as already 
mentioned, rests on the dorsal zone. The plates are 
rather short, occupying only the median portion of the 
frustule, and never reaching its extremities ; the margins are 
usually entire (fig. 17), sometimes more or less sinuated 
(fig. 16). ‘The transverse hyaline space which separates the 
two plates is always distinct, rather broad, excavated in the 
* P. Cleve, ‘Synops. of the Navicul. Diat.’ part i. p. 145. 
1 H. Peragallo, ‘Les Diat. mar. de France, 1. p. 56. 
{ I am using here the term Naviculoid not in the sense given by 
Cleve in his ‘Synopsis of the Naviculoid Diatoms,’ who uses it as a 
synonym of the Raphidian diatoms, but in the more restricted sense 
which is given to this term by Peragallo in his ‘ Diatomées marines de 
France,’ p. 2. 
