BRANCHIOCERIANTHUS IMPEEATOR (aLLMAN). 247 



spongy appearance. I can not think that this appearance of the 

 endoderm is caused by bad preservation, for the tentacles fixed 

 with sublimate show also the same structure. In the preserved 

 state, the endoderm forming the upper ceiling of the lower cavity 

 of the hydranth has a thickness of o mm. 



In the cross and longitudinal sections (Figs. 11 & 12) of the 

 marginal tentacle, the whole of the space inside the mesoderm 

 is entirely filled up with a tissue which reminds one of the verte- 

 brate notochord. It has the same structure as the spongy en- 

 doderm of the hydranth-cavity already mentioned. Only near 

 the base of the tentacle, this spongy tissue leaves in the center 

 a small cavity which is separated by the mesoderm from the 

 hydranth-cavity. Hence the cavity of the tentacle-base is of a 

 limited extent, extending not farther towards the distal end, and 

 communicating nowhere with the general cavity of the hydranth. 

 A longitudinal section (Fig. 2) through the margin of the disc 

 shows plainly the relations of the disc and the base of the tentacle 

 (the mesoderm being drawn darker than other parts in the figures). 



The gonosomes (Fig. 1, p.) as already mentioned consist 

 of the branched tubular stalks, upon which the gouophores 

 are grouped in a crowded cluster. Each stalk branches dicho- 

 tomously into about the lOtli or 12th order. Each branchlet 

 terminates in a group of small globules, of which we recognize 

 two kinds (Figs. 13 & 14). The one kind of which there is only 

 one in each cluster is situated on the top of the terminal branch, 

 while the others take a more lateral position. The former is 

 larger than the latter, consisting of the irregularly shaped cells 

 mostly vacuolised (Fig. 14, e.g.). In this kind of globule the 

 mesoderm of the branch is no longer recognisable and the ecto- 

 and endo-derm can not here be clearly distinguished. It seems. 



