246 M. MIYAJIMA : 



Within the circle of the gonosomes (Fig. 0) the upper himella 

 stands entirely separated from the basal, on which the vertical 

 lamella shows itself only as a ridge-like line which in cross- 

 section is recognizable as a simple small knob. 



Preserved in formalin, the fine tissnes of the animal were 

 unfortunately mostly gone. Luckily, however, the pieces of the 

 gonosomes and the marginal tentacles, which were preserved in 

 sublimate, etc., helped us to ascertain something of the histological 

 character of the animal. 



The wall of the animal-body, I need hardly say, consists of 

 the three layers, ecto-, endo- and mesoderm as in other Coelen- 

 terates. 



The ectoderm, the outermost layer, has been entirely shed 

 oti' from the s[)ecimen in formalin, but in the pieces fixed with 

 sublimate was well preserved. This tissue is a shigle layer of 

 cylindrical cells which in their preserved condition are more or 

 less vacuolised. There are present a few nematocysts which are 

 characteristic of the ectoderm of Coelenterata. 



The mesoderm is a very firm, supporting layer which is 

 placed between the ecto- and endo-derm or two portions of the 

 endoderm. This tissue was well enough preserved even in 

 formalin so that the structure of the animal could be largely 

 made out by this layer alone. 



The endoderm, the innermost layer, which lines the whole 

 cavity of the animal, remained unfortunately only here and there 

 in the specimen in formalin. From these patches it could be 

 made out that the endoderm lining the hydranth-cavity is several 

 cells thick (Figs. 3 & 10). The cells are irregularly formed and 

 contain but a little cytoplasm which is pressed towards the wall 

 with the nucleus. Consequently the wall of the cavity gives a 



