40 SYSTEMATIC SYNOPSIS. 



Order 4. CHEILOSTOMATA, Busk. 



Gymnolaemata in which the orifice is guarded by an operculura. 

 Zooecia dimorphic, some being modified into avicularia and 

 vibracularia. 



Suborder I. Athyriata. Cheilostomata with the front wall 

 uncalcified or incompletely calcified. 

 Fam. 1. Membraniporidce. 

 2. Microporidte. 



