CERATINA. 97 



Sub-order 2. SPINTHAROPHOKA. 



Usually corticate. Megascleres, as a rule, collected in fibres radially arranged 

 from the base to the surface. Microscleres, when present, as some form of aster, 

 never a sigina, sigma spire, or chela. 



Tribe 1. ACICULIN.ffi. With cliactinal megascleres. 



Fain. 1. Epallacidae. Megascleres as oxeas, and microscleres as some form 

 of asters. Epullax Soil.; Scolopcs Soil.; Doryplercs Soil.; Amj)hius Soil.; 

 Asteropus Soli. ; Coppatias Soil. 



Fani. 2. Stylocordylidae. Sponge differentiated into a head and stalk. 

 Skeleton in head radiately arranged with a cortical layer of smaller spiciiles set 

 radiately to the surface. Spicules in stalk set longitudinally in a dense axis. 

 Oxeas only. Stylocordyla W. Th. 



Fam. 3. Tetliyidae. Megascleres are strongyloxeas radially arranged. 

 Microscleres are spherasters, and sometimes other forms of Euasters. Tethya 

 Lam.; Columnitis 0. S.; Xenospongia Gray ; Magog Soil. ; Sollasella Lend. 

 Tribe 2. CLAVULINJE. With monactinal megascleres. 

 Fam. 1. Spirastrellidae. Non- boring sponges with numerous microscleres 

 (asters, spirasters, or discasters), typically forming a more or less continuous 

 dermal crust. Hymedcsmia Bow. ; Spirastrclla 0. S. ; Latnincalia Bocage ; 

 Podosponyia Bocage, etc. 



Fam. 2. Suberitidae. Without microscleres of the aster type. 



Sub-fam. 1. Suberitinae. Skeleton not radially arranged. Suberites 

 Nardo ; WebereUa Yos. ; Poterion Schlegel, etc. 



Sub-fam. 2. Polymastinae. Skeleton radially arranged. Polymastia 

 Bow. ; Quasillina Norman ; Tcntorium Vos. ; Ridleict Dendy ; Trichostemma 

 M. Sars, free-living, deep-sea, symmetrical forms with fringe of hair-like 

 spicules for attachment in the mud ; Tcthyspira Tops., etc. 

 Fam. 3. Clionidse. Boring sponges, generally with microscleres of the aster 

 form. Cliona Grant ; Thoosa Carter ; Alcctona Carter. 



Order 4. CERATINA.* 



Sponges with a supporting skeleton formed of spongin fibres which 

 are without spicules ; ciliated chambers saccular or piriform ; micro- 

 scleres present or absent. 



This is undoubtedly an artificial order, and contains forms which 

 are more closely allied to various families of the Monaxonida than 

 to each other. It includes the so-called horny sponges. 



Fam. 1. Aulenidae. Vestibular spaces complicated ; ciliated chambers very 

 small ; skeleton reticulate, formed of more or less areniferous horny fibres which 

 do not contain proper spicules. Proper eehinating spicules may, however, be 

 attached to the superficial fibres. Allied to the Desmacidonidcc. Aulena Lendf. ; 

 Hyattella Lendf. 



Fam. 2. Spongidae. With small piriform or spherical ciliated chambers ; 

 without proper spicules ; not clathriform. Allied to the Homorrhaphidce. 



Sub-fam. 1. Eusponginae. Skeletal network close-meshed, fibres solid, 

 generally with foreign bodies in the main fibres. Chalinopsilla, Lendf. ; 



* R. von Lendenfeld, A Monograph of the Horny Sponges. Royal Society, 

 London, 1889. 



H 



