REVISION "BRITISH SPONGIADiE." 195 



monactinals in the ectosome, and possesses no 



microscleres. 



Lissomyxilla spinosa, B., LXXXIII. 



Genus Plumohalichondria, Carter. 

 Main skeleton formed of plume-like columns, containing 

 smooth diactinal spicules, echinated by spined styli. 

 Dermal skeleton with smooth diactinal spicules and 

 spined styli. Microscleres isochelse. 



Plumohalichondria fictitia, B., XXIII and LXXXII. 

 fraudator, B., LXXXIII. 

 kenti, B., LXXXIX. 

 Genus Stylostichon, Topsent (18, p. 111). 

 Main skeleton formed of plume-like columns, containing 

 spined styli, echinated by spined styli. Dermal skeleton 

 with smooth diactinal spicules. Microscleres isochelae. 

 Stylostichon ambiguum, B., XXY. 



„ plumosicm, Mont., XXIV. (Kidley and 



Dendy, 14, p. 145.) 

 Genus Microciona, Bowerbank. 

 Main skeleton formed of short plume-like columns, 

 containg basally spined styli, echinated by entirely spined 

 styli. Dermal skeleton with smooth styli. Microscleres 

 may be present : isochelae, with or without toxa and 

 sigmata. 

 Note. M. Icevis differs from the three other species by 

 having smooth -styli in the skeleton columns. 

 Microciona armata, B., XXIII. 



,, atrasanguinea, B., XXIV. (Hanitsch, 8, 



p. 207.) 

 fallax, B., XXIII. 

 Icevis, B., XXIII. 

 Genus Hymeraphia, Bowerbank. 

 Sponges thin, encrusting. Main skeleton formed of 

 isolated monactinals, spined at least at their bases, arising 



