M. Lacaze-Duthiers on the Structure o/ Antipathes. 199 



in the collection of the Maseum, there must exist great differ- 

 ences in the size of the polj'pes in the different species — as, for 

 instance, in Antipathes scoparia, Lamarck, and A. glaberrima, 

 Esper {Leiopathes glaberrima, G.). When the tentacles are con- 

 tracted, the polype only forms a lai^ 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. 



Til is arrangement is very remarkable. In investigating the 

 development of the Actinia, 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 oesophagvs 

 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 short, 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. 



