30 ART. 1. — I. IJIMA : HEXACTINELLIDA, III. 



the dermalia and of the parenchynialia made up of hexactiiis, 

 and of hexactins only, which are quite extensively ankylosed 

 except in growing parts of the body. It may be remarked that, 

 through the two genera herewith united to the Dactylocalycida?, 

 this family is brought into close relationship Avith the lyssacine 

 family which I shall call the Leucoj^sacidœ. 



The four remaining genera, viz., Leucopsacus, Ckaunopleciella, 

 Chulocalyx and Flacopegma, are all lyssacine forms, but should 

 likewise, I think, be removed from the EossellidiB on account of 

 a somewhat marked difference in the nature of the dermal skeleton, 

 a point to which we give, I'ightly I believe, much weight in 

 distinguishing the families. The removal would be an advantage 

 to the system in this respect, that the Rossellidoe is thereby left 

 a group much more uniformly characterized than before, in that 

 its dermal skeleton may then be said to be uniformly composed 

 of well differentiated, small, rough-surfaced dermalia and of nuicli 

 larger, supporting spicules, the hypodermalia, which are generally 

 pentactins much less specialized in characters fiom certain ])ar- 

 enchymalia. On the other hand, the four genera in question 

 have all relatively large peniaclin'w dermalia with which are 

 associated no spicules that may be called the hypodermalia. 

 Owing to this character they can not, in my opinion, very well 

 be received into any known lyssacine family. However it inay 

 be said that in general features of the dermal skeleton, as in 

 fact in general spiculation, they most closely resemble, and there- 

 fore sliow nearest relationship to, the Euplectellidie, but of course 

 with this difterence that the dermalia lack the distally directed, 

 tsixtli rays which are always present in those of the hunily just 

 mentioned. If they should perforce be united to any of the 

 accepted families, the union nuist be with the EuplectellicUe and 



