STILL FOUND IN A LIVING STATE. 369 
On the other hand, an important distinction in the formation of these 
minute Polythalamia and of the many-chambered house of the Nautilus 
will be immediately recognised ; inthe microscopic animalcule the body 
fills distinctly all the single cells, the four front ones with transparent 
colourless, the hinder ones with less transparent coloured parts ; while 
in the true Nautiloidea all the posterior compartments are, as succes- 
sively quitted dwellings, empty, and the first front one alone receives 
the entire animal. 
a. The siphons or tubes of connexion of the individual animals 
in the shell. 
f. The filamentoid cirrhi, which may be lengthened, shortened 
or ramified at will, effecting locomotion, and which are still more 
local organs than the pseudopodia of the Amebe or Arcelline among 
Infusoria. 
é. Bands of aggregated large apertures near the septa of the 
chambers. 
e. Numerous small apertures over the entire surface of the shell 
penetrated by exceedingly minute tubes. 
Fig. 6. A similar animal, magnified 100 times, from the left side. 
The four anterior cells are likewise filled with colourless, the remain- 
der with coloured parts, which cannot optically be distinctly separated. 
However, in all the figures the dark portions of the coloured body are 
granular, and belong probably to the ovarium, while the fainter co- 
loured appear to belong to the organs of nutrition. 
Fig. c. The same creature from the right side. 
Fig. d. The same, front view, on the narrow side. 
a. The anterior apertures of the individual animals. 
Fig. e. A similar creature, seen from the right side, after removal 
of the calcareous shell by means of weak acid. It is remarkable, that 
the first cell, in the natural state apparently empty, likewise exhibits as 
its contents a gelatine quite solid, and somewhat condensed by the acid. 
y- The conoid connecting parts of the chambers, the true siphons, 
of which the sheaths designated by a in fig. a are those of the shell. 
__ Fig. f. The contents ofa single chamber (front view) separated from 
the other parts by too violent a removal of the shell by a somewhat 
strong acid. It may be compared with the anterior part of fig. d. 
‘The connecting parts of the single chambers y y y appear like dentoid 
cones, each of which marks the connexion or the termination of an in- 
dividual. 
Fig. g. The similar dissolved chamber, which consists of several ad- 
herent or not perfectly separated animals, each of which has its conoid 
embouchure or connecting tube with the other joints at y yy: side 
view. 
PLATE VI. 
This Plate contains five native (German) recent calcareous-shelled 
Polythalamia, represented in the living state, of which four likewise 
occur in the chalk in such quantity that they belong to those forming 
| the masses. The first and largest form has however not yet been ob- 
served in the chalk. 
| _ Especially remarkable is the formation of externally affixed ovaria in 
the first form, and the presence of external organs of locomotion, as 
