POLYZOA. 105 



OEDEE. PHYLACTOL2EMA. 



The lophophore is horse-shoe shaped. There is a 

 tongue-shaped lobe in front of the mouth, known as the 

 epistome. The forms included in this order are found 

 only in fresh-water and do not occur fossil. 



OEDEE. GYMNOL^MA. 



The lophophore is circular. An epistome is present. 

 There are three sub-orders, (1) Cyclostomata, (2) Cheilos- 

 tomata, (3) Ctenostomata. The last is not known in the 

 fossil state. 



SUB-OEDEE. CYCLOSTOMATA. 



The zocecia are tubular, their apertures are round and 

 terminal, not constricted and not provided with opercula. 

 Vibracula are absent, and generally also avicularia and 

 ooecia. 



Fenestella. Zoarium funnel-shaped or fan-shaped. 

 Branches straight, united by cross-bars, so as to form a 

 network. The cross-bars do not bear zocecia. On each 

 branch there is a median ridge or carina, on the sides of 

 which the zocecia occur. Openings of zocecia round. 

 Silurian to Permian. 



Fascicularia. Zoarium large, generally massive and 

 globose. Zocecia in the form of long tubes, with horizontal 

 tabulae, in contact laterally, and forming bundles which are 

 either distinct and radiate from the base to the periphery, 

 or fuse into laminae which intersect. Coralline Crag. 



SUB-OEDEE. CHEILOSTOMATA. 



The zocecia are more or less oval, never tubular, their 

 apertures are contracted and provided with a movable oper- 

 culum. Avicularia, vibracula, and ooecia are often present. 



