526 POLYZOA 





[ Colony erect . . . . . .8 



*. 1 Zooecia in several layers forming confused masses . . 30 



( Colony entirely adherent, 1 the zooecia usually in a single layer 31 



Erect Cheilostomata. 



f Branches cylindrical, calcareous, divided by chitinous joints. Orifices 

 arranged all round the branch . Cellaria (Fig. 239, A) 



Branches flexible, jointed or unjointed. Orifices not arranged all 

 round the branch . . . . . .9 



^ Calcareous, unjointed, rigid . . . . .21 



Branches leaf-like, flattened . . . . .10 



Branches not leaf -like . . . . .11 



( Avicularia resembling birds' heads, movable . Bugula (Fig. 233) 

 | Avicularia not resembling birds' heads, unstalked ; or absent. Colony 

 I broadly leaf-shaped, composed of a single layer or of two layers 

 I of zooecia .... Flustra (Fig. 232) 



1 I Zooecia in pairs, at the same level . . . .12 



' ( Zooecia not obviously paired . . . . .13 



{Branches numerous, straight. Zooecia back to back, with an oblique 

 aperture. No avicularia . . . Gemellaria loricata 



Branches delicate, curved. A pair of stalked avicularia between eacli 

 two pairs of zooecia . . Notamia bursaria 



. . , . ., , f conspicuous . . . .14 



13. Avicularia or vibracula-! . , - _ 



\ inconspicuous or absent . .17 



f Avicularia resembling birds' heads, movable. Vibracula absent 1 5 

 I Avicularia large, unstalked. Vibracula present or absent . 16 

 14.-! Avicularia inconspicuous. Setae of the vibracula large, very con- 

 spicuous, on oblique vibracular zooecia, which almost cover the 

 \ backs of the branches . . . Caberea (Fig. 242) 



Zooecia in two series, alternate, with one or several conspicuously 

 long marginal spines .... Bicellaria 



15. -| Zooecia in two or more series. Aperture occupying most of the front 

 of the zooeciuin. Colony often spiral. Avicularia usually large 



Bugula (Fig. 233) 



Zooecia long, narrow below, commonly in triplets, with two lateral 

 avicularia to each triplet. Fornix present . Menipea ternata 



Zooecia biserial, a considerable number forming an internode 

 separated by a joint (often inconspicuous) from the next internode. 

 Lateral avicularia usually large. Vibracular zooecia on the back 

 or sides of the branches . . Scrupocellaria (Fig. 254) 



[ Characters as in Scrupocellaria (No. 16), but with inconspicuous 

 17. J, avicularia. A branched fornix . Scrupocellaria reptans 



[ Vibracula absent . . . . . .18 



f A single, short, marginal spine ; or none . . .19 



' \ Marginal spines present . . . . .20 



1 Certain varieties of adherent species occasionally assume an erect form. 



16. 



