GoRGONiA. ZOOPHYTA. GORGONIADiE. 511 



Gen. PORITES. — Massive, obtuse, stellular discs regular, 



subcontiguous, with imperfect margins ; the plates of the 



stars filamentous, chafFy, or cuspidated. 



1. P. cellulosa. — Cells angular, walls thin; true structure not yet dis- 



covered. Park. Org. Rem. ii. 39. t. v. f. 9. — Carboniferous Limestone^ INIas- 



bury, Men dip. 



Gen. XXXI. POCILLOPORA.— Branched, the surface co- 

 vered with stelliferous deep-seated discs, with the interme- 

 diate spaces porous. 



72. P. interstincta. — Cylindrical, with distant immersed 

 stars. 



Madrepora interstincta, Mull. Prod. Zool. Dan. 252. 

 A specimen, probably of this species, which I have seen, was obtained by 

 Dr Hibbert in Zetland, a detailed description of which, I had reason to ex- 

 pect, would by this time have been published. 



GORGONIAD^. 



Gen. XXXII. GORGONIA.—Cells for the polypi sessile. 

 The axis is, in some species, of the hardness of horn, or 

 wood, in others of the softness of leather. In its young 

 state, at the ends of the branches, it has a soft central pith. 

 . It consists of concentric layers, homogeneous, tubular, or 

 consisting of osseous spicula. The flesh consists of two 

 plates, an external and internal. The external plate is 

 more or less thickened with cretaceous matter, under dif- 

 ferent forms, and bears the cells, for the protrusion of 

 the polypi, either simple and imbedded, or in the form of 

 warts, with notched or spinous margins. On the inner 

 plate (termed by Ellis periosteum) may likewise be ob- 

 served perforations (through which it is probable an inti- 

 mate connection subsists between the polypi and the in- 

 terior of the axis), and a crowded arrangement of perpen- 

 dicular tubes, which are supposed destined to secrete the 

 corneous matter of the axis. Between these plates the 

 fleshy matter is pulpy, with interspersed osseous spicula in 

 some species. 



a. Cells imbedded, with simple margins. 



73. G.Jlahelliim. — Venus's Fan. — Compressed, branches nu- 

 merous, and reticularly united. 



