I have on other occasions described some of the more characteristic phenomena of this class of creatures;—the volcanic eruptions of the Crumb-of-bread Sponge, the hills and poles and webs of the Rosy Crumb, the protrusile bladders of the Sanguine, the starry spicula of the Flat-Sack.[157] These I shall assume as known, and shall confine myself to the enumeration and description of a few other species which are found congregated on this rocky roof.
One of the first to catch the eye, by its gorgeous colour, is a rather thin, soft, spreading patch, of the richest vermilion hue.[158] It is of close substance, the surface covered with shallow irregular sinuous channels and minute orifices. It rarely exceeds an inch in diameter, but throws out slender clinging processes to some length. The flesh is dense. Under the microscope it contains three-rayed spicula, which are for the most part somewhat blunt, but some are very sharp. After death it rapidly loses its brilliant hue, and dries of a dull oak-brown.
Another occurs in the form of low irregular spreading patches of a greyish black, very smooth and shiny, more plump than the former, and a little larger.[159] There are no visible orifices on the surface. The substance is yellowish grey, compact, with a distinct demarcation from the thin black tough skin. The spicula of the flesh have three rays in one plane, and one standing up from it; very stout, sharp-pointed, with a distinct canal running through the centre of each ray of the larger ones. There are a few rods abruptly hooked at the tip; a few very long, straight, and slender, with pin-like heads; and a few simple needles, long, slender, pointed at one or at both ends.
Some largish rounded masses occur, several inches in diameter, and rising to a thickness of three-fourths of an inch.[160] The surface is undulate, the summits slightly ridged, covered with shallow sinuous channels having sharp edges, not very confluent: large round mouth-orifices (oscula) generally mark the summits of the ridges. The colour of this fine species is a deep buff, and its appearance is much like that of our Turkey Sponge, with something of the same feel, but much firmer. The interior is full of channels. The spicula here are very varied and interesting, comprising some curious and unusual forms. Some, indeed, are simple needles, nearly straight, pointed at one end rather abruptly. The following are minute. There are a number of rings interrupted at one side, like the letter
, some thicker and more elliptical, others slender and rounder,
. A few take the form of the letter
, but having one lobe much more developed than the other. Some of the