320 ZOOLOGY SECT. 



Sub-Class I. Ectoprocta. 



Colonial Polyzoa with the anus outside the lophophore, with a 

 well-developed introvert and a spacious coelome. 



ORDER 1. GYMNOL^EMATA. 



Almost exclusively marine Ectoprocta, with a circular lopho- 

 phore, and without an epistome. 



Siib-order a. Cyclostomata. 



Gymnolsemata with tubular calcareous zocecia having circular 

 apertures devoid of closing apparatus. 

 Including Crisia, Idmonea, &c. 



Sub-wder b. Cheilostomata. 



Gymnolsemata with calcareous or chitinous zocecia usually pro- 

 vided with opercula. 



Including Bugula, Flustra (" Sea-mat ") Membranipora, Cellepora, 

 Selenaria. 



Sub-order c. Ctenostomata. 



Gymnolaemata with chitinous or gelatinous zocecia provided with 

 a series of tooth-like processes closing the aperture when the 

 tentacles are retracted. 



Including Alcyomdium, Serialaria, Paludicella. 



ORDER 2. PHYLACTOL^MATA. 



Fresh-water Ectoprocta with horse-shoe-shaped lophophore and 

 with an epistome. 



Including Cristatella, Plumatella, Fredericella. 



Sub-Class II. Endoprocta. 



Colonial or solitary Polyzoa multiplying by the formation of 

 buds which in Loxosoma soon become separated off, while in 

 Pedicellina they remain connected together by a creeping stolon. 

 The anus, as well as the mouth, is internal to the lophophore. 

 The introvert is slightly or not at all developed. A pair of ciliated 

 nephridial tubes are present. 



Systematic position of the Example. 



Bugula avicularia is an example of the sub-order Cheilostomata 

 of the Gymnolsemata. It is a member of the family Bicellariidae 

 which is characterised by the erect plant-like colony, with narrow 

 compressed branches, and attached by root-like fibres : by the 



