A chart of the Rugose corals. — Sherzer. 
28T 
DISSEPIMENTS. | TABULA. 
CENTRAL AREA. 
Outer zone of structure- 
less sclerenchyma ; 
probably vesicular. 
Variously formed and ex- 
tending only to peripheral 
zone. 
Septa not twisted at center. 
None. 
Nearly complete. Strongly 
. convex upwards. 
Large, spongy columella. 
None. 
Apparently but a single one 
forming floor of calyx. 
Smooth or with a pseudo-col- 
umellar structure. 
No true vesicular 
structure. 
Convex, irregular. Complete 
with more or less inter- 
ruption. 
Central, compressed, non-con- 
tinuous columella. 
None. 
Elevated and crescent- 
shaped in one-half of 
calyx. 
Smooth, no columella. 
No true vesicles. 
Horizontal, well developed. 
No columella. 
None. 
None or rudimentary. 
A false, spongy columella. 
None. 
Obsolete or rudimentary be- 
low base of cup. 
Primaries become complin 
cated or contorted. 
Coarse and formed 
mainly by the contin- 
uous cell cups. 
Cell cups form distinct tab- 
ulae through the center. 
False columella formed by 
twisting of primaries. 
Thick, structureless 
endotheca in periph- 
ery. 
Not extending across the en- 
tire visceral cavity. 
No columella. 
None. 
Horizontal and embracing. 
Plainly developed and ex- 
tending to the wall. 
Columella present and formed 
of little tubes. 
No true dissepiments. 
Sometimes complete, but 
usually poorly developed 
and even obsolete. 
A spongy central core occu- 
pies the axis. 
No true vesicles. Indi- 
cated by branching 
tabulae. 
Generally complete and well 
developed. Horizontal. 
Septa may be slightly twisted. 
No columella. 
Present in periphery. 
Present in central area. 
More or less deveh >ped. 
Incomplete and rather 
l rly developed. 
Septa generally leave a free 
open space. 
Remote, angular, but 
becoming dense in 
outer zone. 
Strung, non-vesicular, in- 
complete. Elevated and 
twisted. 
Conical, obliquely contorted 
eminence. 
Minute vesicular tis- 
sue in periphery. 
( lontined to center, close-set, 
vesicular. Somewhat con- 
cave upward. 
Elevated. Formed by tabu- 
he and a lew radial, ver 
tical plates. 
Very simple if any. 
Moderately developed. 
No eohimella. 
More or less developed 
( 'onlined to Central area, thin 
and irregularly horizontal. 
A tube-like, nearly central and 
columellar-like wall. 
Rather coarse in exter- 
nal area. 
Strong, remote and confined 
to center. 
A comparatively gigantic 
strong columella. 
Very simple if presenl 
at all. 
Frequently complete and 
formed of the cell cups; 
Sal at center. 
Smooth, or with septa reaeli 
ing center as low ridges, 
