414 
THE VOYAGE OF H.M.S. CHALLENGEE. 
which exceptionally they may be present, and if several such cases be found, and in all of 
them the microsclere belongs to the same group of forms, we may make use of it for 
further investigation of the affinities of the family ; thus the Axinellidse are usually 
without microscleres, but in every instance in which they possess them these spicules are 
some form of aster, hence, ceteris paribus, their affinities are with the Spintharophora 
rather than the Meniscophora ; the Suberites are defined by Eidley and Dendy as 
being without microscleres, but Carter has described as a Suberites [Suberites 
stellifera) ^ a sponge in which euasters occur, and in the very characteristic Suberites 
virgultosa (Bowerbank), centrotylote microstrongyles are present and these are 
derived either from a spiraster or a euaster ; if from the former I suppose it might be 
remarked that the species should be included in the Spirastrellidse ; if so, that only 
supports the argument for assigning the Suberites to the Spintharophora, for it admits 
the close relationship of the Suberites to a family distinguished from it by the 
possession of spirasters. 
The difficulty of determining whether a Spintharophorous sponge not possessing 
microscleres should be assigned to a family distinguished by spirasters, or to one 
distinguished by euasters, renders the subdivision of the Spintharophora into groups of 
higher value than families extremely difficult. 
The first subdivision may be naturally made into those genera in which 
spicules of two widely different orders as regards size are present, and those in which 
the spicules are all of the same order ; the latter may be termed Homosclera, the 
former Heterosclera ; the Homosclera are as at present known represented by a single 
family — the Astropeplidse, with a single genus and species, but it is possible that the 
species of the genus Coppatias, none of which I have seen, may eventually be found 
to belong here. The Heterosclera may be divided into two demi, the first the 
Centrospinthara, in which the asters are euasters, and the second the Spiraspinthara, in 
which the asters are some form of spiraster. The Centrospinthara will include the two 
already existing families, Axinellidse and Tethyidse, and a third new one, the Dory- 
pleridse. The Spiraspinthara wdl include the two existing families, Suberitidse and 
Spirastrellidse, and a third new one, the Scolopidse, which appears to be intermediate 
between the other two. 
I have already shown in the Introduction to the Tetractinellida the reasons which 
preclude the acceptance of Vosmaer’s two orders, Silicispongise and Cornucaspongise, or 
the Chondrospongise and Cornucaspongise of von Lendenfeld, and I have now to explain 
why I do not see my way to accepting the two suborders of Vosmaer, the Halichon- 
drina and Clavulina, although these have been adopted by Ridley and Dendy. The 
Clavulina being that which includes aster-bearing sponges is the only division with 
which we are immediately concerned. It is defined by my colleagues as follows ; — 
^ Carter, Ann. and Mag. Nat. Hist., ser. 5, vol. x. p. 124, fig. 2, 1882. 
