STILL FOUND IN A LIVING STATE, 337 
‘chains. They have a rather rapidly-closing perfect self-division, 
and are characterized thereby. They are only found as single 
free discs. Each pair of round plates connected by a broad ring 
forms an individual; and in the living specimens self-division was 
observed on the margin, which, according to the analogy of the 
Gallionelle, is longitudinal division, with the appearance of hori- 
zontal division. At the outermost border of each disc was per- 
ceptible a circle of numerous minute apertures in the shell. A 
very finely divided, much-folded body, probably the ovarium, of 
a brownish or greenish colour, filled at times the entire inner 
space; but generally in the centre of the disc was a more trans- 
parent, usually ill-defined spot, comparable to the cicatricula in 
the egg, as in Navicula, which appears to be the chief part of the 
true animal body whence the other organs proceed to the peri- 
phery. A glandulous globular body, sometimes more sometimes 
less developed in the interior, appearing gray by transmitted 
light, was a singly-developed sexual gland, a large contractile 
simple oval vesicle once observed was the sexual vesicle, and 
small scattered transparent cells were analogous to gastric cells. 
Motion and locomotive organs were not distinguished. 
The systematic character of the fossil genus Actinocyclus had, 
even in 1837*, been so correctly ascertained from its fragments 
found in Oran, that the inspection of the living species has not 
altered it. The only doubt that remained as to the fossil forms, 
was, whether in the living state they did not constitute chains, of 
which the contrary is now certain. In structure the A. senarius 
almost entirely resembles Coscinodiscus, the only difference being, 
that the inner space is divided by the radiating septa into six 
equal parts, and the ovarium into just as many larger folds, di- 
vided again into many other folds. Here also were perceived 
the brownish or green eggs which filled the disc, a transparent 
colourless spot in its centre, and scattered transparent cells 
(gastric cells). No gland, however, was distinguishable, nor 
locomotive organs. The organization of the fossil Gallionella 
sulcata appeared quite similar to that of the other Gallionelle. 
V. On the Locomotive Organs of a large Navicula from Cuxhaven. 
The opinions of observers being still divided as to the true na- 
ture of the Bacillarie, which become more and more important in 
geological researches, and the reasons advanced by me for their 
animal nature not having been attended to by some modern ob- 
* Berichte der Akademie, 1837, p. 61. 
