JOURNAL OF THE COLLEGE OF SCIENCE, IMPERIAL UNIVERSITY; 

 TOKYO, JAPAN. 



VOL. XVIII., ARTICLE 1. 



Studies on the Hexactinellida. 



CONTRIBUTION III. 



{Placosoma^ a New Eiiplectellid ; Leiicopsachlw and 

 Cffulo2>7iacif1œ). 



By 



Isao Ijima, ^''g-- -P/?- D-. Rig.- Hah., 

 Professor of Zo()logy, Imperial TTniversitv, Tokyo. 



With 8 plates. 



In this contribution I propose first to describe a new stalked 

 Euplectellid of an interesting structure, which I call Placosoma 

 paradictyum. This form became known to me after I had 

 provisionally consid(!red my studies of the Euplectellidœ at end. 

 It may however be best to describe it now and to follow it with 

 some comments on the family generally, before I enter upon a 

 treatment of other families. 



The present contribution will further contain full descriptions 

 of six other forms, partly likewise new and parth^ before described 

 by me in brief, viz., Leucopsacus orthodocus Ij., L. scoliodocus 

 Ij., Chaunoplectella cavernosa Ij., 61 spinifera n. sp., Caulophacus 

 loli folium n. sp. and Synipagella anomala u. sp. These will be 

 referred to two families newly conceived and proposed for introduc- 



