AMPHIBOLITE

term for a metamorphic rock consisting e entially of divers acce ory minerals, (e.g.) felspars, iron oxide, biotite, etc. Owing to its different modes of origin and structural character representing different stages of metamorphism, a. cannot be strictly defined. council of ancient Greece, a ociated with a shrine, the temporal affairs of which were in its charge. The members were chosen from the principal neighboring tribes, and there were such councils at Delos, Argos, and, most famous of all, at Delphi. distributed marine animal between 14% and 3 in. in length, somewhat fish-like in appearance. and inhabiting shallow water (c. 2 fathoms) with a sandy bottom. Its structure is of extreme interest, as it exhibits numerous affinities with vertebrates, of whom it may be regarded as a primitive, though degenerate offshoot. About sixteen species are included in the subphylum Cep halo chorda (A crania, Pharyngobranchii) of the phylum Chord at a. A. is faintly flesh colored and translucent, pointed at both ends with a dorsal median fin and two meta pleural folds ventrally, and has 62 V-shaped muscular segments (myotomes). The rigidity of the body is maintained by a dorsal rod notochord composed of turgid cells surrounded by a sheath running from tip to tip. A dorsal tubular nerve-cord without a definite brain lies above it. The mouth is overhung by a hood bearing a fringe of ‘cirri’ and a ‘velum’ for wafting in the food. The walls of the gullet are perforated by numerous gill slits, and the water is ejected through the ‘atriopore’ in the 36th myotome, while the food is wafted along ciliated grooves through the straight intestine to the anus situated near the atriopore. The only known sense-organs are sensory cells in the epidermis. There is a rhythmically contractile branchial artery with colorle blood, instead of a heart. Excretion is carried on by a complex arrangement of about 90 pairs of ‘nephridia’ situated in the wall of the pharynx. The sexes are separate and the ductle gonals (ovaries and testes) are arranged in 26 pairs of sacs along the ventral side of the body. The development is of great theoretical interest.