INTEODUCTION. 
xli 
Suborder TUBULATA. — Zooecia simple and tubular. Monomorpbic. 
Section A. — Apertures scattered or in lines, and not in groups. 
Fam. Crisiida.—ZoQjium usually articulate, with chitinous 
joints, attached by radical tubes. 
Fam. Diafitoporid ^. — Zoarium linear or in bands or sheets. 
Sheets adnate or erect, and occasionally superposed. 
Fam. Idmoniidce . — Zoarium adnate or erect. Apertures only on 
the obverse face, and arranged in transverse or divergent rows. 
Fam. Entalophorid(e . — Zoarium erect and dendroid. Apertures 
occurring all around the stem. 
Fam. Eleidce . — Apertures sub -terminal or lateral. Avicularia 
and spines present. 
Section B. — Apertures in crowded bands. 
Fam. TheonoidcB . — Zoarium adnate or erect. Apertures con- 
fined to crowded bands along raised ridges or the edges 
of the fronds. 
Section C. — Apertures in groups at the ends of fasciculi. 
Fam. FascigeridcB . — Zoarium fasciculate ; fasciculi free for 
most of their length. 
Fam. Osculiporidce. — Zoarium fasciculate; fasciculi closely 
attached and the apertures on raised processes. 
Suborder CAXCELLATA. — Zooecia with cancelli. 
Fam. Petaloporidce . — Zoarium erect and branched. Apertures 
on all sides of the stem. 
Fam. Horneridce . — Zoarium erect and branched. Apertures 
only on the obverse side. 
Fam. DesmeporidcB. Zoarium fasciculate ; apertures in groups 
on raised processes. 
Suborder DACTYLETHBATA. — Zoarium provided with dacty- 
lethrae. 
Fam. Reticuliporidce.—Zo2iTi\im. of compressed branches; 
apertures confined to obverse parts of branches. 
Fam. TerebellariidcB . — Dactylethrse in crowded bands around 
the stems. 
Fam. ClausidcB . — Zoarium erect or adnate. Zooecia distributed 
uniformly and separated by circles of dactylethrae. 
