222 



PORIFERA 



109. — Microscleres of Demospongiae. a, b, Sigmaspires viewed in different directions ; 

 c,d, bipocilli viewed in different directions ; c,toxaspire ;./',/', spiraster ; //, sauidaster ; 

 h, anipliiaster ; i, sigma ; j, diancistra ; k, isocliela ; I, m, anisochelae viewed in 

 different directions ; n, cladotyle ; o, toxa ; fj, forceps ; q, oxyaster ; r, spheraster ; 

 s, oxyaster with 6 actines ; t, anotlier with 4 actines ; it, another with rays reduced 

 to two (centrotylote microxea) ; v, tylote microrhabdus ; u\ tricliodragmata ; 

 X, oxeate microrhabdus or microxea. 



11. 



fMicroscleres sigmata .... Craniella cranium 

 (Sigmata absent, asters present . . . . .12 



[Microscleres include sjiirasters . 

 \ Microscleres include sterrasters . 

 [ Microscleres include euasters : sinrasters and 



[Two kinds of euaster present .... SteUetta 



4 Microscleres include a euaster and a sanidaster or amphiaster 

 y Stryphnus 'ponderosus 



(Microscleres include microrlialxli . Pachymatisma johnstoma 



Poecillastra compressa 



. 14 



terrasters absent . 13 



(Microscleres include many-rayed euastei's 



( Some of the microscleres asters . 

 ^^ Microscleres absent, or not asters 



[Skeleton radiate ; asters of more than one kind 

 I Sponge encrusting ; asters of one kind only 

 [skeleton fibrous 



[Megascleres all diactinal ; chelae present 

 - ]\Iegascleres all diactinal ; chelae absent 

 [Some or all of the megascleres monactinal 



Cy (Ionium miller i 



. 16 

 . 17 



Tdhya 

 . Hifmedesmia 

 . Axinella spj). 



. Desmacidon 

 . 18 

 . 19 



