82 THE PHORIOSPONGIiE, 



one exception these spicules belong to the monactinellid type. 

 The fibrous skeleton of these Sponges is sometimes composed of 

 " hollow " fibres which do not contain any foi-eign bodies, some- 

 times again of solid fibre with or without foreign bodies. The 

 number of foreign bodies in the fibre may increase to such an 

 extent, that hardly any Spongiolin is left between the sand particles. 

 In those cases we are not able to distinguish between main, radial 

 and connecting, tangental fibres. There is only a coarse and 

 irregular network of arenaceous threads to be seen, which may 

 contain different kinds of foreign bodies. There are a great many 

 Australian Sponges with a skeleton of this kind. 



Very often we find in these Sponges the well known filaments 

 characterizing the family Hircinida ; generally there are no flesh- 

 sj)icules, but sometimes the latter are met with in these arenaceous 

 Sponges. Often the spicules appear massed around the arena- 

 ceous fibres and form a dense coating around them : we have 

 arrived at true Phoriospongiae. 



I do not hesitate to consider the Phoriospongise as belonging to 

 the horny Sponge as well as those porifera which, like Dysidea 

 possess an arenaceous skeleton but no flesh-spicules. 



From the point of view taken up by Marshall (I.e.) and others, 

 all these horny Sponges with flesh-spicules might be combined to a 

 iamily for itself. I have however convinced myself of the correct- 

 ness of my original idea, that within any family of Ceraospongife, 

 Sponges with flesh-spicules may be produced. A', e find namely 

 that these flesh-spicules are extremely variable, and that there 

 exists no correlation between them and the structure of the Sponge 

 apparently. 



I consider the Phoriospongire, not as boring Sponges living in 

 sand ; but as Ceraospongise belonging to the group with arenaceous 

 irregular fibres. 



Vosmaer has recently in a short paper " on the relation between 

 certain Monactinellidse and Ceraospongice " (Mittheilungen der 

 Zoologischen Station in Neapel, Band 5, Seite 490-492), advanced 

 the hypothesis that the horny Sponges are the descendants of the 

 siliceous Monactinellidse. 



