ANALYSIS OF THE GENERA. 
TonhvcU's of ono khul, innrgiunl. 
Colmnu thick, pcar-shnpoil. 
Mouth with a papillate gonidial tube Pftu'hia. 
ilouth simple Ilt/anthns. 
Column slender, long, worm-shaped. 
Invested with an epidermis Pdwardsia. 
Without an epidermis JlalcuiHjia. 
'I'entacles of two kinds, marginal and gular. 
Naked; freely swimming Arachnactis. 
Dwelling in a membranous tube ; sedentary. 
Column inferiorly perforate Cenanthus. 
Column inferiorly imperforate {Not Jh'ittsh) . . Sixccanthug. 
