526 POLYZOA 



,i 



II. 



12. 



Colony erect ...... 



Zooecia in several layers forming confused masses . . 3( 



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



Erect Cheilostomata. 



r 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 



k Calcareous, unjointed, rigid . . . . .21 



j 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 



broadly leaf-shaped, comj>osed of a single layer or of two layers 



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



j Zooecia in pairs, at the same level . . . .12 



( Zooecia not obviously paired . . . . .13 



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



aperture. No avicularia . . . Gemellaria loricata 



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



two pairs of zooecia Notamia ( Epistomia) bursaria 



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



13. Avicularia or vibracula^' . r . , ,_ 



^ inconspicuous or absent . .17 



i* Avicularia resembling birds' heads, movable. Vibracula absent 15 

 Avicularia large, unstalked. Vibracula present or absent . 16 



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

 spicuous, on oblique vibracular zooecia, which almost cover the 

 backs of the branches . . . Caber ea (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 zooecium. Colony often spiral. Avicularia usually large 



Bugula (Fig. 233) 



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

 avicularia to each triplet. Fornix present. Menipea temata 



J 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) 



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



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



[ Vibracula absent . . . , . .18 



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



' \ Marginal spines present . . . . .20 



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



