ACTIN'IA, a genus of marine animals, belonging to the sub-kingdom calenterata (see SUB KINGDOMS, ANIMAL), and to the class ac-tinozoa, of which latter group the genus is thoroughly typical. The animals included in this genus arc familiarly known as " sea anemones. ' They are found attached by their bases to rocks and stones, and present the appearance of cylindrical fleshy bodies, possessing a mouth surrounded by numerous tentacles in the free extremity. These tentacles in the genus A. are of simple, tubu lar conformation. They are perforated , at their tips, and also possess sucker-like disks. The mouth leads into a stomach- •- , sac, which (as in all coelenterate animal) A' \ "IP - .( ,. ,..- .. i .... • communicates freely below with the general C . .4.0 -,--4: . • \'''' ,,,,! ,. r and this comes to resemble a pocket with the bottom cut out. The . '....a_ stomach-sac is kept in its place by a series ,. ,...:,.. .-_ ., of vertical radiating plates, named ? „..; I, e ,.. - ,---- tk.- t '1-4 -
or mesenteries, to the faces of which the • t reproductive organs arc attached. The Actinta seen from above. SECTION OF AcrrNis: actiniadm are capable of slow movements a, cavity of stomh , b, by expanding and contracting the muscu surrounding bers.
lar bases of their bodies. They may be cut and divided in various ways, with the result of producing new individuals by artificial fission. Some species may attain a great age, as proved by the well-known case of a com mon A. (II. mesenthryanthemum), which was taken from the firth of Forth by Sir John G. Dalvell in 1823, and is still (1878) alive, in the possession of Dr. 11PBain of Trinity, near Edinburgh. This remarkable animal "grannie" by name—has at various times given birth to numerous young; and as more than one of her progeny have in turn become parents, her cognomen is not merely complimentary.