95 



appear however in Hiantopora, Rugularia (PI. V, fig. 2 a), Petalostegus (PI. IX, 

 figs. 8 a, 8 b) and sometimes in Chaperia. The ocecia are as a rule hyperstomial, 

 and might be considered as free, because the endoooecium only has a small 

 portion of its basal wall in common with the frontal wall of the zooecium. 

 Whilst the endoooecium is always calcareous, the ectoooecium may be calcified 

 completely (Bicellaria ciliata) or almost completely (Dimetopia cornuta), or some- 

 times quite or partially uncalcified (Dendrobeania Murrayana, Bugularia dissimilis, 

 etc.). In a smaller number of cases the ocecia are immersed either in kenozooecia 

 or in ordinary zooecia (^Bugiila' mirabilis). With the exception of most Chaperia 

 species and of » Membrampora« Carted^, whicih on account of its pedunculate, 

 capitate avicularia must certainly be referred to this family, the colonies are 

 never incrusting and appear in a greater variety of forms of growth than in any 

 other family of the Cheilostomata. Apart from such genera as Gemellaria, Notamia 

 and Synnotiim, in which the colonies may be considered as two-layered, colonies 

 with two layers are only found in Watersia militaris and Dimorphozoum nobile. 

 Radical fibres appear in most genera and in very different ways (see the synopsis 

 of the genera). 



This family, like the Aeteidae, presents a series of points of contact with the 

 Ctenostomata, and forms so to speak a connecting link between these and the 

 Cheilostomata. This is nowhere more prominent than in the peculiar dimorphism 

 in Dimorphozoum nobile (PI. IV, figs. 1 a— 1 e), as the zooecia in the one layer of 

 the colony are built in quite the same way as in an Alcgonidium, whilst in the 

 opposite layer they possess an operculum, avicularia and ocecia. For the rest, 

 however, the diaphragm in these zooecia seems to be Ctenostome-like. We should 

 also remember that an operculum is absent in species of the genus Bugula, as 

 also that the diaphragm in Eucratea chelata is said to be built in the same way 

 as in the Ctenostomata. The generally slight calcification also agrees with this 

 view, and finally a series of forms in this family shows quite similar modes of 

 connection between the zooecia as those we know in the majority of the Cteno- 

 stomata. Thus, Beania corresponds in this regard with the Ctenostome genera 

 Arachnidium and Buskia, whilst the stolon or stem, which consists of kenozooecia 

 and which is widely distributed in the Ctenostomata, is again found in ^Bicellaria'^ 

 glabra, Bugula (Stirparia) Haddoni and B. (Stirpaia) caraibica. 



When Busk, Hincks and other writers refer a number of genera of the 

 family (Eucratea, Gemellaria, Notamia, Didymia, Dimetopia etc.) to other families, 

 the reason is, that these writers have laid greater stress on the form of colony 



1 23, p. 82. 



