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



occur which stain in the same manner as the granular gland cells, but no cell wall has 

 been observed (cf. PL XIV. fig. 6). 



Mesoglcea. — The mesoglcea of Antvpathes is similar to that of other Antipathinae, but 

 in many cases transverse striae have been observed to occur in it at irregular intervals 

 (PL XIV. fig. 6, me). It appears possible that these may be artificial products, but they 

 have not been observed in other genera. The mesoglcea is of considerable thickness in 

 this genus (31 to 42 /a). 



Entoderm. — The entoderm is relatively thin and consists chiefly of irregular hyaline 

 gland cells situated near the base of the layer, above which a number of small cubical 

 cells usually occur (PL XIV. fig. 6, e). These may correspond with the epithelial cells of 

 Antipathdla, but their outline is not well defined in the specimens examined. The 

 entodermal muscular layer is rudimentary and, as in Antipathella subpinnata, is most 

 readily observed in vertical sections of the stomodasum. 



The inner aperture of the stomodaeum is somewhat funnel-shaped, and the lower 



border is continued for some distance along the free lower margin of the transverse 



mesenteries and is also continued on to the directive mesenteries. Its course is 



best studied by means of a consecutive series of sagittal sections. Starting from the 



stomodaeal lumen the sections first pass through the wall of the stomodaeum and a little 



later sections of a transverse mesentery are reached. The mesentery consists of a thin 



vertical plate of mesoglcea clothed on each side by a rather thin layer of entoderm of 



normal structure. Its base is fused with a moderately thick transverse plate of tissue, 



which is a reflexed portion of the stomodaeum. The mesoglcea of the mesentery and 



stomodaeum is thickened at the point of fusion. The upper surface of this transverse 



plate is clothed with a layer of entoderm, thicker than that of the mesentery. The 



lower surface consists of stomodaeal ectoderm cells, which present the characteristic 



staining with borax-carmine. A little nearer to the lateral extremity the two directive 



mesenteries, which proceed from the angles of the stomodaeum, are well marked. They 



consist, like the transverse mesentery, of a delicate strand of mesoglcea clothed on 



each side with entoderm, and reach to a point slightly below the recurved stomodaeal 



plate, with which they are fused. A thickening is formed at the lower border of each 



directive mesentery, consisting of entoderm cells above and of stomodaeal ectoderm cells 



beneath ; the lower ectodermal border is markedly curved. The recurved stomodaeal 



plate next loses its connection with the directive mesenteries, and in the succeeding 



sections becomes gradually reduced in diameter until it forms a thickening of the lower 



border of the transverse mesentery, which is no thicker than the terminal dilation of a 



mesenterial filament. Ultimately both directive and transverse mesenteries have a free 



thickened border consisting of cells derived from the ectoderm of the stomodaeum and 



apparently similar to the median lobe of the Actinian mesenterial filament. 



Ova. — The ova are relatively large and frequently measure 0'25 mm. in diameter. 



