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less proximally on the basal surface of the zooecium. The lateral walls always 

 independent, and each provided with 1 (rarely with 2) multiporous rosette-plate, 

 which is often partially uncalcified. The avicularia when present dependent, most 

 frequently capitate, pedunculate, freely movable, more rarely sessile and in that 

 case often extremely long and slender. The ocecia as a rule hyperstomial, free, 

 more rarely endozocecial and then as a rule covered by kenozocecia. The colonies 

 free or creeping, generally branched and frequently provided with radical fibres. 

 With a few exceptions (e. g. Hiantopora and Chaperid) the calcification in this 

 family is very feeble, and the least calcified Clieilostomata known are undoubtedly 

 the Beania species, of which some contain so little calcareous material that it is 

 only by using hydrochloric acid that we can make sure that there is any calci- 

 fication at all in their walls. Whilst the whole frontal wall in the Beania species, 

 in Dimorphozoum nobile and Watersia militaris, is membranous, in most members of 

 the family a larger or smaller portion of it is calcified and forms a gymnocyst, 

 which may sometimes, for instance in Gemellaria loricata and certain Cornucopina 

 species, occupy two-thirds or three-fourj;hs of the whole length of the zooecium. 

 From this gymnocyst in older zooecia there arises not so seldom a small secund- 

 ary cryptocyst (e. g. in Didymia simplex, Gemellaria loricata, Dendrobeania Murray- 

 ana). Except for the species of the genus Beania in which the individual zooecia 

 are connected by cylindrical tubes, two zooecia in the same longitudinal row are in 

 all other cases connected by a distal wall, which is always more or less ascending 

 from the basal towards the front wall so that the distal end of the lower zooecium 

 projects more or less over the proximal end of the zooecium above. It is usually 

 furnished with a number of uniporous, more seldom with one or two multi- 

 ^ porous, rosette-plates and not rarely {Bugula, Halophila, Didymia, Bicellaria, Bicel- 

 larina, Bugularia) the basal edge shows a peculiar angular bending (PL III, figs. 

 1 c, 2d, PI. V, figs. 1 a, 2 b). Each lateral wall is as a rule provided with 1 or 

 rarely with 2 multiporous roselte-plates. Except for the pore-ring they are as a 

 rule membranous, and it is therefore difficult to decide, from spirit-material, 

 whether they are uni- or multiporous. In all cases where they are calcareous, 

 e. g. in Dendrobeania Marrayana, Dimorphozoum nobile, Bugularia dissimilis etc., 

 they are however multiporous. Whilst the dependent avicularia in most Cheilo- 

 stomata attain their greatest breadth where they are fixed to the zooecium, most 

 avicularia in this family are provided with a shorter or longer movable peduncle 

 or the proximal part of the avicularian chamber is slender pedunculiform. While 

 the first have the peculiar resemblance to a bird's head which has given rise to 

 the name ^avicularium» the others which increase gradually in breadth toward the 

 distal end have been described as trumpet-shaped. Common sessile avicularia 



