believed them to be part of the coral itself, and called a specimen of Astraea which was full of them, Madrepora polygama (Amœn. Acad. iv. 250, t. 3, f. 15), denying at the same time that they could be Lepades! because of the absence of the valves, the small size of the holes, and the surface of the cavity being rayed. Savigny, in the large work on Egypt, appears to have properly understood their structure: since his time the various kinds have been minutely examined, and placed in different genera. Those inhabiting stony corals form a tubular sheath or base, as it is called, which is elongated at the top by the secretion and deposition of fresh shelly matter on the edge of the tube, as the coral grows: those that live in sponges form hemispherical bases, which are enlarged in the same manner: and those which fix themselves in the stems of Gorgoniæ form a slipper-shaped base, to enable them to clasp the thin stem, and at the same time maintain a sufficiently erect position to allow the animal freely to collect its food.
In the instances cited the coral has followed its usual course, and the animals have only taken up their abode in its substance; but Spengler long ago described a coral under the name of Madrepora cochlea, which appears to be a Cyathophylla, whose form has been modified by some worm taking up its abode in its base, and forming within the lower side of the coral a cylindrical spiral cavity. The base of the coral is slipper-shaped, with a large round hole communicating with the tubular cavity near the projecting part of the slipper. The star is more or less irregular, formed of many unequal rays, with a compressed perforated centre; besides this hole there is a series of minute pores on the upper surface of the margin, and often some others in the centre of the base, which appear to communicate with the tubular cavity. I have lately received from China, with the specimens above described, another species, agreeing with the former in most particulars, but differing from it in the coral being more solid and hard, and the whole of its surface being covered with continued longitudinal ridges, with finely crenulated edges, extending from the edge of the star to a little within the margin of the flat base. The star is formed of more lamina, which have a number of shorter columnar processes placed between them, especially near the central depression. The large hole enters obliquely, and is furnished with a regular shelly sheath (not found in the other species), and the holes communicating with the tube are only to be observed on the hinder half of the erect sides of the coral, and not at all on the base. I would propose to call this Cyathophylla Spengleri, in honour of N. Lorenzo Spengler, the excellent Danish conchologist who first described the
