REPORT ON THE ACTINIARIA. 43 



structure. I have been unable to detect generative organs in any specimen 

 investigated. 



" Owing to the abundant incrustation, the body-wall becomes as hard and brittle 

 as stone, and does not permit therefore of investigation by means of sections. In this 

 case therefore, and in the remaining forms with similarly strong incrustation, I made 

 use of the method of grinding tested and recommended by G. v. Koch in his researches 

 on Tubipora. 



" The body- wall is of considerable thickness ; its mesoglcea exhibits a structure very 

 different from the remaining species of Epizoanthus, as being penetrated by deposits 

 throughout its whole depth. These deposits consist of particles of sand with irregular 

 angles, and are set in a strong circular fence, reducing the mesoglcea to thin lamellae ; but 

 there persists a very narrow internal lamella bounding the endoderm all round. In the 

 homogeneous lnesoglcea-lamellas are situated roundish cells which give off fine radiating 

 processes, and fine fibres provided with nuclei ; the presence of the cell-heaps, which 

 are to be met with in the remaining species of Epizoanthus, I was unable to 

 demonstrate in this case. A transverse section through the wall of the shell exhibits 

 a similar condition in the ccenenchyme. This latter is also of considerable thickness, 

 and is internally traversed by the large endodermal tubes which connect the various 

 ccelentera together. 



"The body-wall is, as has been already mentioned, bent above at a sharp angle, 

 thus forming a plate-like surface. In contrast to the remaining members of the 

 genus, where it turns deeply inwards vertically, it is here only slightly invaginated, a 

 difference resulting from the slighter development of the sphincter. The latter com- 

 mences to a certain extent on the horizontal part of the body-wall, and then thickens 

 gradually into a truncated muscular mass, which appears fusiform in section, and is 

 only slightly curved inwards. It lies enclosed in the innermost lamella of mesoglcea ; 

 the latter is thus much thickened, and is free from adventitious deposits. The 

 sphincter is on both sides bounded by a layer of mesoglcea, which extends inwards to 

 the commencement of the oral disc, is charged with the usual accretions, and is a direct 

 continuation of the outer sandy layer." 



So much for the anatomical description given by Erdmann, which sufficiently 

 proves that Epizoanthus cancrisocius must be separated systematically from Epizoanthus 

 parasiticus, the latter possessing larger and coarser polyps and far less incrustation. I 

 have identified the animal with the Epizoanthus cancrisocius of Studer, as he records 

 for his specimens similar dimensions, and a marked incrustation, at least for the basal 

 membrane. 1 In other points his description is not sufficiently exhaustive, and this is 

 still more true of Gray's account. 2 Only the statement of the latter that the large 



1 Monatuber. d. k: Akad. d. Wiss. Berlin, 1878, p. 547. 

 s Proc. Zool. Sue. Lond. 1867, p. 237. 



