9G THE VOYAGE OF II.M.S. CHALLENGER. 



cannot be definitely determined after preservation in spirit, but would require material 

 preserved in osmic acid. 



After the ovum has passed into the supporting lamella, it still reaches the bases of the 

 epithelial cells by means of a narrow process, the cells having undergone the modifica- 

 tions already described (fig. 8). The cells are fine filaments, with few granules, and 

 compressed into a body shaped like a gustatory bulb ; they are much more numerous than 

 in Corallimorphus. 



The part of the filamental apparatus formed of epithelial cells lies originally in the 

 same plane as the opaque, granular, epithelial cells, but later, when the ova increase in 

 size, it occupies the bottom of a depression in the epithelium, surrounded by the neigh- 

 bouring cells which have increased in length. On the other hand, it never passes over into 

 the mesoderm, so that the filamental apparatus remains in a condition which leaves room 

 for further differentiation in Corallimoiyhus. On the larger ovicells there is a narrow 

 cortical layer which is distinguished from the central parts by a structure only indistinctly 

 preserved in spirit. Radial lines indicate, however, that the protoplasm has become divided 

 into small rod-shaped pieces. 



Whilst acontia are wanting, the configuration of the mesenteric filaments is the same 

 as in other Actiniae. I was able to make out a marginal stoma by the help of transverse 

 sections in the upper part of the septa, but I could not determine whether a perioral 

 stoma exists or not. 



After the septa are free from their reproductive organs, their mesenteric filaments, 

 and their stronger, specialized muscular cords, they still extend as far as the centre point 

 of the rounded posterior end of the body. Two of the septa are connected in such a way 

 as to form a partition wall separating the four septa on the one side from the six septa 

 on the other (PI. III. fig. 10). This arrangement precludes the existence of a central 

 posterior pore, but in place of it I found numerous eccentric openings, which are, however, 

 so small that they could not be perceived on the surface, even under a strong magnifying 

 glass. I observed them by making sections transversely through the posterior body-wall 

 of the larger animal, and parallel to the convex terminal surface of the smaller. 



The openings are placed in a circular zone at a Httle distance from the centre point. 

 In sections parallel to the surface I found two of them in the same radius, one outside 

 the other, and I therefore presume that there are about twenty-four of them ; each radial 

 chamber probably containing two (PI. XIII. fig. 5). This point cannot, however, be easUy 

 determined from preserved material, as in such a case the wall is pleated, and also from 

 its convex curvature is not well adapted for making such sections. 



If we prepare a series of transverse sections, we have a successive view of a large 

 number of openings, often two in the same transverse section, placed symmetrically left 

 and right from the middle ; from the relation of their positions to the septa, which can 

 also be seen in transverse section, we may assume that they are regularly distributed 



