222 



PORIFERA 



CHAP. 



a 



8 



d e p f 



a 



flfc 



6 



p 



to 



X 



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

 c,d< bipocilli viewed in different directions ; e, toxaspire ;/,/', spiraster ; g, sauidaster ; 

 h, amphiaster ; i, sigma ; /, diancistra ; k, isochela ; I, m, anisochelae viewed in 

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

 s, oxyaster with 6 actines ; t, another with 4 actines ; u, another with rays reducet 

 to two (centrotylote microxea) ; v, tylote microrhabdus ; to, trichodragmata 

 x, oxeate microrhabdus or microxea. 



11. 

 12. 



13. 



14. 

 15. 



16. 

 17. 



Poecillastra compress 



f Microscleres sigmata .... Graniella craniut 

 (Sigmata absent, asters present . 



TMicroscleres include spirasters . 



4 Microscleres include sterrasters .... 

 ( Microscleres include euasters : spirasters and sterrasters absent . 1 



(Two kinds of euaster present .... Stelletb 



4 Microscleres include a euaster and a sanidaster or amphiaster 



Stryphnus -pondero 



(Microscleres include microrhabdi . Pachymatisma 



^Microscleres include many-rayed euasters 



( Some of the microscleres asters . 

 \ Microscleres absent, or not asters 



T Skeleton radiate ; asters of more than one kind 

 A Sponge encrusting ; asters of one kind only 

 [Skeleton fibrous 



{Megascleres all diactinal ; chelae present 

 Megascleres all diactinal ; chelae absent 

 Some or all of the megascleres monactinal 



Cydonium millet 



. 11 



. I 1 



Tethya 

 Hymedesmia 

 Axinella spp. 



Desmacidon 

 . 18 

 . 19 



