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FAMILY III.— TURBINOLIAD^. 
In tliis, and all the families which have now to come 
under consideration, the tissues secrete calcareous matter, 
which unites into a solid internal skeleton of stone, known 
as the CORALLUM. The stony substance is chiefly deposited 
— 1. in the integuments of the base and column, forming 
the WALL {mums) ; 2. in the septa, forming a series of 
perpendicular plates (lamellce), which radiate iinvard from 
the wall ; and, in some cases, another circle, or circles, of 
similar plates, PALULES {pali), which do not 'reach the 
wall ; and 3. (as I believe) in the ovarian mesenteries, form- 
ing a series of plates, generally twisted, in the bottom of 
the cavity, called the columella. The hollow centre, 
formed by the upper edges of the plates, is called the 
CALICE {calyx). Sometimes the exterior of the wall is 
furnished with longitudinal RIBS (costce), which correspond 
to the plates. 
The plates are arranged in cycles : those of the Jirst 
cycle project furthest inwards ; those of the second bisect 
the interspaces ; those of the third bisect the interspaces 
thus formed, and so on. The whole of the plates developed 
in one primary interspace constitutes a system. 
In the TuRBiNOLiAD.a2 the corallum is solid (not porous), 
simple, with the lamellar interspaces reaching to the 
bottom of the cavity, and perfectly free. The plates are 
highly developed, simple, and generally have a granular 
surface. The ribs are well-marked. 
X 2 
