200 I. IJIMA : HEXACTINELLIDA. I. 



It must be said, that in the above merely a beginnnig has 

 been made in the study of the development of spicules in the 

 Hexactinellida. A series of important questions on the subject 

 remains to be answered in the light of facts which still lie wholly 

 in the dark. 



Miscellaneous Notes. 



E. marshalli is a species which evinces a very close affinity 

 to E. oweni Herkl. & Marsh. But the two species are not to 

 be confounded, on account of the former having a comparatively 

 shorter body in proportion to its breadth, strikingly well developed 

 parietal ledges, and oscularia which, instead of being predomi- 

 nantly diactins, are of miscellaneous forms. 



From E. imjjerialis it may be distinguished, in all stages of 

 growth, by the somewhat smaller floricome (p. 103) ; and in the 

 mature state, by marked dißerences in the size and shape of 

 body, in the appearance of the parietal ledges and in the fused 

 or un fused condition of spicules in the skeletal framework (see 

 the key on p. 58). 



As in E. imperialis, here also several instances of the re- 

 paration of injuries sustained by the sponge-wall have come 

 under my observation. 



In some cases it appeared that a portion of the wall had 

 been torn oft' and lost, but refilled by regeneration so as to com- 

 pletely restore the continuity of the wall. The regenerated tract 

 can be recognized at once by its generally underdeveloped 

 appearance, which at the edge abruptly passes over into that of 

 the old parts. In it the texture is not so firm as in parts of 

 long standing ; the ledges are either quite undeveloped or only 



