196 THE VOYAGE OF H.M.S. CHALLENGER. 



indicate the presence of ectodermal muscular fibres in this species. In some cases, 

 in transverse vertical sections stained in borax-carmine, I have noticed at the base of 

 the ectoderm of the body-wall what appear to be a few slender muscular fibres cut 

 rather obliquely, but the point requires further study. It is interesting to note that 

 this is precisely that part of the ectoderm which does not contain a muscular layer in 

 Actiniaria according to the brothers Hertwig. Such a layer is undoubtedly present in 

 the ectoderm of the body-wall of Antipathes dichotoma (cf. PI. XIV. fig. 6, f), and 

 other forms, and may therefore be presumed to have a greater or less development in 

 Anti'patliella. 



I have failed to recognise any ciliated epithelial cells (Stiitzzellen) in the external 

 ectoderm of Antipathella sityrinnata, but such cells appear to be present in the 

 ectoderm of the stomodseum, although they are not recognisable in borax-carmine 

 preparations. The surface of the ectoderm is probably ciliated, but it is difficult to 

 study such points in specimens which have been preserved for a long time in strong 

 spirit. 



Stomodzeum. — In Actiniaria the ectoderm of the stomocheum has a similar general 

 structure to that of the peristome, but the muscular layer is absent. The epithelial 

 layer is of considerable thickness, but is only one-layered, and contains " Stiitzzellen," 

 nematocysts, and two kinds of gland cells. The nervous layer is readily recognised, 

 but the ganglia are not numerous. The stomodaeum of Anti'pailiella, subjrinnata 

 presents an interesting structure, and differs in one or two important points from that 

 of Actiniaria. In the first place, nematocysts are entirely, or almost entirely, absent. 

 The stomodseum of Antipathina3 may readily be distinguished from the ectoderm of 

 the external surface, on account of the fact that it stains more deeply with borax- 

 carmine or hematoxylin than any other portion of a section, with the exception of 

 the free margins of the mesenterial filaments. The ectoderm consists here chiefly of 

 two kinds of glandular cells, the one hyaline, the other densely stained. In borax- 

 carmine preparations (PI. XIII. fig. 10) the greater part of the layer is seen to be 

 occupied by large oval hyaline gland cells, each with a deeply-stained nucleus. They 

 rest on a delicate layer of nerve-fibres adjoining the mesoglcea, and fill up the lower 

 half or two-thirds of the epithelial layer. The cell plasma does not stain, but here 

 and there indications of a semigranular coagulum may be noticed. Threaddike cells 

 are placed between the large gland cells, as in the ectoderm of the tentacles and body- 

 wall, but are not so easily seen. The hyaline cells are similar to those in the epithelial 

 layer of the tentacles, but are broader, and do not usually reach the surface. The 

 surface of the ectoderm in this region is apparently occupied by a large number of 

 small lens-shaped cells, which stain very deeply in borax -carmine ; some of them belong 

 to a second and smaller type of gland cell filled with granules. In many cases wedge- 

 shaped clusters of these small and deeply-stained cells extend for some distance 



