OX A NEW SPECIES OF CORYMORPHA FROM JAPAN. 



159 



three layers, the ectoderm, the endoderm and the mesoglcea ; they are 

 nothing other than outbulgings of the body-wall. In a quite small 

 papilla, the cytoplasm of the ectodermal cells is homogeneously 

 granular ; the outer part of it stains considerably deeper. The meso- 

 glcea is only feebly developed as compared with that of the general 

 body-wall. Inside the mesogloea is a sigle row of endodermal cells 

 which proximally pass over insensibly into the epithelium of longit- 

 dinal canals. At the apex of papillae we find a narrow space which 

 invariably shows a flattened endodermal cell closely applied to the 

 mesoglœa. The same space is found also in the more elongated 

 papillae. As the papilla grows longer, ectodermal cells with much 

 cytoplasm become restricted to the tip only, they being replaced in 

 other parts by those with coarsely reticulated cytoplasm. The axial 

 endodermal cells become more vacuolated towards the basis of papilla. 

 Finally let it be only added that ectodermal cells differ greatly in 

 their character in the papillated and non-papillated regions, as has 

 already been observed by other writers. 



To compare the present form with other species of the genus : 



1) . Corymorpha nutans Sars is undoubtedly more closely allied 

 to the present species than any others. However, several important 

 points of difference are to be noticed : in coloration of the hyclrosome, 

 the number of proximal tentacles, the number and arrangement of 

 gonosomes, the shape of the medusa-umbrella, the mode of anastomosis 

 of longitudinal canals in the hydrocaulus, etc. 



2) . Corymorplia nana Alder differs markedly from the present 

 species in being of a diminutive size and of a white or yellowish color, 

 in the less number of tentacles of both sorts (16-18 distal tentacles in 

 two imperfect rows and 1 5-20 proximal tentacles), and in sessile or 

 unbranched gonosomes. 



3) . Corymorpha carnea Clarke differs from the present species 

 in being of a coral-red color and in having about 30 gonosomes. 



