Madreporal

As the Nautilus headed for Clermont-Tonnere, one of the curious islands of the group discovered in 1822 by Captain Bell of the Minerva, I prepared to study the madreporal system that has created these particular isle.

The instrument is about twenty feet above sea level, and is built on ground composed of hard madreporal rock.

Liquid fuel, such as the residues of petrol, etc., is absorbed by some porous incombustible substance, such as pumicestone, tufaceous or madreporal material, or bones from which the grease, gelatine, and moisture have been removed, and the resulting product used as a substitute for coal.

Looking out to sea, the eye rests on a fringe of madreporal shelves over which the blue waves, broken farther out in a line of silvery foam, come lazily.

Between these vascular rings there is a long muscular heart, which, united to the calcareous pouch or cord, extends from the madreporal plate to the mouth.

Its constituents are all coalesced into one piece, the madreporal filter spreading its pores over its central forepart.

The water-vascular system communicates with the exterior by a separate canal through a single pore or a cluster of pores, the hydropore, situated in the so-called madreporal inter-radius.

Dorsal view with genital plates and large, sievelike madreporal plate in the center, below which is the large, anal field (periproct), shaded dark.