20 SCHULTZE, ON DIATOMACE. 
the middle. Once only I saw three individuals hanging 
together, and of these one was caught again in the act of 
dividing. Their lengths were 0°15, 0°15, and 0°225.” On 
the siliceous coat I could not perceive a rimged marking. 
The poimting at the ends is waved, and the extreme point, 
. sharply marked off, as in R. styliformis, is bent like a bird’s 
claw. The level of the curves of these points in the two ends 
of one individual are not parallel, but cut themselves at a 
sharp angle. The two specimens delineated at fig. 8 present 
a provisional, not clearly explicable peculiarity. They were 
found without organized contents. They adhered firmly to 
one another, as they are figured, being only slightly changed 
that the cause of their cohesion may be shown. ‘The length 
of the specimen on the left was 0°2’”, that on the right 0°25’. 
In both the upper point was broken off nearly at the middle ; 
but a kind of termination was again effected by a very delicate 
membrane. Both contained in the interior, moderately near 
one end, two spikes of new individuals made fast to each other 
im an inverted direction. I suppose these examples were 
caught in the act of dividing, for which purpose they had 
developed the new spikes in the middle. They may be released 
later from their original situation by the death and subsequent 
maceration of the contents. Lastly, the young points differed 
from one another. Asis evident in figs. 9 and 10 (magnified 
330 diam.) the point of the former has a double, strongly 
refracting contour, while that of the latter is paler and more 
delicate. Fig. 9 lay in the specimen figured on the right 
above, and in that on the left below, a, a. Fig. 10 was the 
reverse, 0, 6. After the division in the Rhizosoleniz, as also 
in Coscinodiscus and Denticella, the siliceous covering of the 
parent individual still remains for a long time uninjured over 
the divided place (compare figs. Gand 12). After this is cast 
off, the offspring of the division always adhere for some time 
to one another. So hkewise in Rhizosolenia styliformis, as in 
fig. 2, where the dotted lines indicate the original union by 
the siliceous covering which is here at present wanting. 
Specimens are frequently seen to whose free ends still adhere 
portions of the already cast-off siliceous covering of the 
parent. Rhizosoleniz broken off, close the opening with a 
siliceous plate arched like a watch-glass. Still they appear, 
in addition, immediately after the closure to develope a new 
and regular terminal process. I have seen specimens of the 
species, at least, which certainly show, if it may be so some- 
what artificially explained, that the broken-off point, getting 
placed inside the tube, may become incarcerated by the 
ensuing closure. 
