15U HYALONEMA. 



Amphidiscophora F. E. Schulze. 



Hexactinellida the spicules of which are always isolated; with amphidiscs; 

 without hexasters. 



Of the two famihes into which F. E. Schulze^ divides this suborder, one, 

 the Hyalonematidae, is represented in the collection. 



HYALONEMATIDAE (Gray) F. E. Schulze. 



Amphidiscophora in which the afferent apertures all lie in one area, the 

 gastral face. 



The collection contains fifty-seven more or less complete specimens and six 

 fragments of this family. iVU belong to the genus Hyalonema. 



HYALONEMA Quay. 



Hyalonematidae with gastral cone, without conuli-like protuberances on 

 the dermal face; with one or, exceptionally, several stalks composed of long 

 intertwined anchoring spicules; with acanthophores in the lower end-part of 

 the body. 



Two specimens cannot be specifically determined. The other fifty-five, 

 and the six fragments, belong to twenty-four species, twenty-two of which are 

 new. 



Hitherto fifty well-defined species of Hyalonema have been described. To 

 these twenty-two are added in this Report, so that there are now seventy-two 

 valid species of Hyalonema. The number of species being so great I en- 

 deavoured to arrange them in subgenera. In attempting to do this I first 

 thought it might be possible to fall back on F. E. Schulze's ' original division of 

 the genus into the subgenera Hyalonema (with a special gastral sieve-mem- 

 brane) and Stylocalyx without such a structure. I found, however, as Schulze 

 himself did on reconsideration,'* that this could hardly be done with advantage. 

 Then I tried to attain my object with the help of the key given in Schulze's 

 Valdivia report,^ but this also helped me only to a small extent. I therefore 



' F. E. Schulze. Hexactinellida. Ergeb. Deutsch. tiefsee-exped., 1904, 4, p. 181. 



 F. E. Schulze. Kept. Voy. Challenger, 1S87, 21, p. 189. 



^ F. E. Schulze. Revision des i3y.stemes der Hyalonematiden. Sitzungsb. Akad. Berlin, 1893, no. 

 30, p. 554. 



' F. E. Schulze. Hexactinellida. Ergeb. Deutsch. tiefsee-exped., 1904, 4, p. 163. 



