48 



l. MIMA. 



siderable extent from allied Kossellids in which the characteristic dis- 

 coctaster is represented by typical discohexasters. Probably the group 

 deserves to receive the rank of a sub-family, but I prefer to put off this 

 question until I have studied all my Eosselid materials. As will be seen 

 in the sequel I have distributed the species in question under three 

 genera. One of these, Acanthascits, although represented by a single 

 species, seems to me to be sufficiently distinct. With respect to the 

 rest, I must say that it would largely depend upon the individual caprice 

 of systematists whether to keep them on as two distinct genera, as I 

 have done, or to make only a subgeneric distinction between them. 



Genus ACANTHASCUS. 



Uiscoctasterophorous Rossellids with exclusively 

 d i a c t i n h y p o d e r m a 1 i a . 



This genus as originally established by F. E. Schulze in the Chal- 

 lenger Report, included besides the species given below, two more forms 

 that were called A. grossularia und A. dub ins. These latter do not 

 possess discoctasters, which seem to be represented here by discohexas- 

 ters. On this account and from considerations of certain other points, 

 it seems to me justifiable to remove them altogether from the genus. 

 I think they might be included among Rossella more naturally than be 

 left in union with a discoctasterophorous species. Prof. Schulze him- 

 self has declared, in his letter to me, to share in this idea now. So then, 

 the genus Acanthascus remains with the following single species. 



1. Acantliascus cactus, F. E. Sch. 



Cup-like, vase-like, or funnel-shaped, often somewhat compressed, 

 with simple oscular edge ; dermal surface with conical elevations, bearing 

 on their apex a tuft of strong, needle-like, prostat oxydiactins. The 

 body may attain a large size of more than 450 mm. in height. It fre- 

 quently bears a limited number of secondary persons. 



Parenchymal diactins small, probably never exceeding 15mm. in 

 length. 



