§ 15. CORALS OR POLYPARIA. 611 



we have the elements of zoophytal organization, and all the 

 varied and extraordinary forms that will hereafter come 

 under our notice, are but modifications of this type of 

 animal existence. In some, the skeleton or support consists 

 of earthy matter as in the Flustra, but solid and hard as 

 adamant; in many examples it branches out like a tree {Lign. 

 136, p. 620) ; in others, constitutes hemispherical masses, 

 having numerous convolutions on the surface, somewhat 

 resembling in appearance the brains of quadrupeds {Lign. 

 138) ; and in many it forms an aggregation of tubes, 

 terminating in star-like openings (PL VI. jig. 9). Among 

 the branched varieties, some are covered by pores so nume- 

 rous as to be called Millepora ; in many, the openings are 

 distant : some have star-like markings here and there ; 

 while in others, the whole surface presents a stellated struc- 

 ture. In many species the fleshy animal matter entirely covers 

 and conceals the stony skeleton during life ; in others, the 

 latter becomes exposed, and forms a trunk, having branches 

 covered by living polypes ; while in another, and numerous 

 division (of which the common Sertularia is an example), 

 the skeleton is secreted by the outer surface of the soft 

 parts, and constitutes an external protection to the polypes 

 (PL V. Jig. 1). In another family, the Gorgonia {Lign. 

 135), the skeleton is of a horny or ligneous texture, and 

 flexible, bending to the motions of the waves ; while in 

 some it is jointed or articulated, as in the Isis {Lign. 136, 

 fig. 3). Sometimes the skeleton is impressed with the 

 cells, as in the Madrepores {Lign. 1 36, fig. 2) ; while in 

 other species, as the Red Coral, the stem is smooth, and 

 exhibits no traces of the peculiar structure of the animal, 



to the polypes themselves ; but in familiar writing the term Coral is 

 often used to designate the entire living mass. The Bed Coral forms 

 a distinct genus called Corallium. In a fossil state the polyparium 

 alone remains, except in a few instances. See " Medals of Creation/' 

 chap. viii. 



VOL. II, S S 



