8. The mya also deposits nidamental capsules; those which are called limnostrea are the first to originate in muddy places, but the conchæ, chemæ, solens, and pectens find their subsistence in sandy shores; the pinnæ grow up from their byssus both in sandy and muddy shores. The pinnæ always contain a pinnophylax, either like a small caris or cancer, and soon die when this is extracted. On the whole, all the testacea are produced spontaneously in mud different kinds originating in different sorts of mud: the ostrea is found in mud, the conchæ and others that have been mentioned in sand. The tethya, balanus, and others which live on the surface, as the patella and nerita, originate in holes in the rocks. All these reach maturity very soon, especially the purpuræ and pectens, for they are matured in one year. 9. Very small white cancri are produced in some of the testacea, especially in the myæ that inhabit muddy places, and next to this in the pinnæ those which are called pinnoteræ; they occur also in the pectens and limnostrea. These animals apparently never grow; and the fishermen say that they are produced at the same time as the creatures they inhabit. The pectens disappear for some time in the sand, and so do the purpuræ. The ostrea (bivalves) are produced in the manner described, for some of them originate in shallow water, others near the shore, or among rocks, or in rough hard places, or in sand; and some have the power of locomotion, others have not. 10. Among those that are not locomotive, the pinnæ are fixed; the solens and conchæ remain on one spot, though not fixed, and do not survive separation from their home. The nature of the aster[165] is so hot, that if it is captured immediately after swallowing anything, its food is found digested; and they say that it is very troublesome in the Pyrrhæan Euripus. Its form is like the paintings of a star. The creatures called pneumones are spontaneously produced. The shell which painters use is very thick, and the pigment is produced on the outside of the shell; they are principally found in the neighbourhood of Caria. [165] Star-fish. 11. The carcinium also originates in earth and mud, and afterwards makes its way into an empty shell, and when it grows too large for that, it leaves it for a larger one, as the shell of the nerita, strombus, and such like; it frequently occurs in the small ceryx. When it has entered the shell, it carries it about and lives in it, except that as it grows it migrates into a larger shell. CHAPTER XIV.