A chart of the Rugose corals. — Sherzer. 277 
Occasionally calcareous opercula occur which articulate with the 
counter septum. 
Fam. I. Inexpleta, Dyb. 
Interseptal spaces empty (occasionally near the base slightly devel- 
oped dissepiments occur). Tabulae and cellular tissue wanting. Septa 
well developed. 
Tribe J . Cyaihaxonince, E. and H. 
Corallum top or horn-shaped, always simple. Septa in the calyx reg- 
ularly radiate, well developed. 
Tribe 2. Pctmince, Dyb. 
Calyx much deepened. The septa begin close to the outer edge of the 
calyx as slightly raised bands and in their downward course become 
complete only in the depth of the calyx. 
Tribe 3. Palccocyelince, Dyb. 
Corallum simple, free, disc-like or bowl-shaped. Septa well de- 
veloped. 
Fam. II. Expleta, Dyb. 
" Filling-tissue" (tabulas, dissepiments, or both) occupy the entire 
space of the visceral cavity. 
Sub-Fam. 1. Diaphragmatophora, Dyb. 
Tabulae completely formed ; dissepiments wanting or quite poorly de- 
veloped. Septa in the calyx regularly radiate. 
Sub-Fam. 2. Plenophora, Dyb. 
Tabulae incompletely formed, present only in the central part of the 
visceral cavity. Vesicular tissue in the peripheral portion. " 
Sub-Fam. 3. Cystophora, Dyb. 
Tabulae wanting, vesicular structure filling the entire visceral cavity. 
Tribe 1. CystiphyLUnce, E. and H. 
The vesicles arranged in vertical, contiguous layers, radial to the 
center. In the calyx the uppermost rows of vesicles project with their 
arches and form endothecal bands. 
Tribe 2. Plasmopliyllinm, Dyb. 
Septa more or less developed or dwarfed. Visceral cavity filled with 
cellular structure. 
Tribe 3. Fletcherince, Zitt. 
Septa dwarfed. Vesicular tissue in the visceral cavity very coarse. 
Tribe 4. Ooniophyllince, Dyb. 
Calyx very deep. Septa at times weakly developed. Vesicular struc- 
ture in the interseptal spaces very dense. Calcareous opercula always 
present. 
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