ROLL GALL 79 



PHYLUM II — PORIFERA — Sponges. 



Characteristics : Usually considered as diploblastic animals ; body con- 

 sists of a perforated (inhalent pores) cylinder, leading to central canal 

 opening to outside through exhalent pore; [peculiar flagellate, collared 

 cells (choanocyfes) typically present; body structure frequently compli- 

 cated by budding ; 2500 species. 



Class I — Calcarea — (Grantia). 



Characteristics : Small marine sponges possessing one-, two-, or four-rayed 

 calcareous spicules. 



Class II — Hexactinellida — Deep-sea sponges (Euplectella). 

 Characteristics : Sponges with six-rayed siliceous spicules. 



Class III — Desmospongia — Finger sponge, bath sponge (Chalina, Spongilla, 

 Euspongia) . 

 Characteristics: Diverse groups of sponges possessing spicules of silicon, 

 not six-rayed, with spongin, or a combination of spicules and spongin. 



