M. Lacaze-Duthiers on the Structure of Antipathes. 199 
in the collection of the Museum, there must exist great differ- 
ences in the size of the polypes in the different species—as, for 
instance, in Aatipathes scoparia, Lamarck, and A. glaberrima, 
Esper (Letopathes glaberrima, G.). When the tentacles are con- 
tracted, the polype only forms a large mamilla, upon which no 
traces of the tentacles are to be distinguished. In many dried 
specimens, however, we may see six tubercles surrounding the 
mouth, which forms a seventh. 
The general cavity of the body in A. subpinnata presents a 
very remarkable arrangement, which has nothing analogous to 
it in any known Coral. When the peristome is examined, six 
lines are seen radiating around the mouth; these evidently cor- 
respond with the peripheral septa which are known to exist in all 
these animals; but four of the lines become effaced not far from 
the mouth, in the midst of the tissues. Two larger ones, opposite 
to each other, alone bear the convoluted filaments; these two 
septa are usually in the plane passing through the axis of that 
portion of the polypary which bears the animal to which they 
belong. 
This arrangement is very remarkable. In investigating the 
development of the Actinie, we find that the formation of the 
peripheral chambers of the general cavity commences by the 
production of two septa, which, retaining the advance that they 
have before the rest, always appear to be more developed, and 
correspond to the angles of the commissures of the mouth. In 
Antipathes these first two septa alone appear to attain complete 
development; the others are scarcely indicated by the lines 
above mentioned. 
In these, as in other Coral-polypes, we find an cesophagus 
leading from the mouth, upon which the inner margins of these 
two septa are attached. It must also be observed that the con- 
voluted body, which is of comparatively very large size, appears 
to occupy the whole of the free margin of the septum. 
The tissue of the walls of the body is of extreme delicacy. It 
is composed of two sets of cells, in which two distinct layers are 
not, as in Gerardia, to be recognized. Of these cells some are 
transparent and turgid with fluid, others opaque and filled with 
granulations. The latter, by bursting and mixing their contents 
with the water, give origin to a viscid mucilage, which is very 
troublesome in making preparations. The cellular tissue is 
covered with very active vibratile cilia, both within and without. 
The nematocysts are ovoid, and of large size. Their thread 
is skort, and its spiral turns are but indistinctly visible through 
the capsule. They are largest in the convoluted filaments, and 
are there regularly arranged almost side by side. In the integu- 
ments they are grouped in parcels, as in Gerardia. 
