phosphorescent sea-pens in all the European seas and Indian Ocean. The Virgulariæ are sea-pens which have long slender stems, with short transverse pinnules, on both sides of their extremity: they have no spicules, and are remarkable for the contractile power both of their axis and polypes. Mr. Darwin mentions a species he met with during his voyage in the Southern Ocean, which seems to be akin to the Virgularia juncea common in the Indian Seas. They were long and slender, projecting in vast numbers like stubble above the surface of muddy sand. When touched or pulled, they suddenly shrunk down with such force as to disappear partly or altogether. Sensitive as these animals are, they have no nerves; hence their motions must be owing to the irritable nature of muscular fibre. The eggs of the Virgularia mirabilis, native on the Scotch and Norwegian coasts, are formed in the fleshy coat at the base of each polype. As soon as they acquire their yellow colour and ciliated surface they enter into its body, and revolve in it for a little time before they come out at its mouth. The family of the Tubipora, inhabitants of warm seas, are the most beautiful of the Alcyons. They consist of rounded masses of considerable size, formed of fragile, hollow, and nearly parallel calcareous tubes. The tubes do not touch one another, but they are united at intervals by horizontal plates, formed of an extension of their bases, dividing their mass into stages. In the Tubipora musica, a native of the Indian Ocean, there are several superincumbent series of equal and parallel tubes, exactly like the pipes of an organ. The whole compound fragile mass is of the richest crimson, and the polypes spread their white tentacles like stars over the mouths of the uppermost pipes, or retreat into them. Buds spring from the upper part of the tubes, and the result is the death of the parents, which are succeeded by a young living race a stage above them. The Tubipora purpurea lives in the Mediterranean and Red Seas. The polypes of a species found by Professor Dana, at the Feejee Islands, have their centre and mouth of a brownish red, and their tentacles yellow, edged by a double fringe of violet-coloured pinnules. [Illustration: Fig. 128. Tubipora musica.] _Actinian Zoophytes._ The great family of the Actinian zoophytes abounds in genera and species. The common Sea Anemone, or Actinia, of which there are more than seventy species on the British coasts, is the model of the minute polypes which inhabit the stony corals, and build the coral reefs and atolls of the tropical Pacific.