GONIA, ALCYONIL'M, and PENNATCLA.
Order III. Ilugosa (Lat. rugosus, wrinkled). This order is extinct, and. excepting holocystis elegans of the eretaceons formation, their fossils do not occur in rocks later than the paleozoic, and therefore are known only by the characteristics of the corallum. The rugosa are divided into four families: 1. stauridte; 2. cyathaxonidre; 3. cyatho phyllidie; 4. eystiphyllidre.
Order IV. Ctenophora (Gr. kteis, a comb, and phero,I carry). " Transparent, oceanic, gelatinous aetinozoa, swimming by Mean,: 0 CithOphOrek or parallel rows of cilia dis posed in comb-like plates" (Greene). The order comprises five families: 1 calymmithe; 2. cestic2; 3. callianirichet 4. pleurobrachiadm; 5. beroidre. See BEnlir.. The ces tidm have a flat, ribbon-shaped - at right angles to the direction of the digestive tract, and three or fcur feet long (Venus's girdle). The pleuroltrachiada the typical family, have a transparent, colorless, spherical, melou-shaped body, in which the two poles of the spheroid are called oral and apical, the rezt, of the body constituting the interpolar region. There is a transverse mouth at the oral pole opening into a fusiforrn digestive cavity, in the lower part of which there are peculiar brown cells performing, it is supposed, the functions of a liver. The interpolar region, or body, is traversed by eight meridianal bands or ctenophores, elevated transversely into a number of ridges, each having a fringe of cilia, forming a comb-like plate. Besides these comb-like ridges, there are two long, tentacular processes, also fringed with curved cilia, forming singu larly beautiful and interesting organs. See CTENOPIIORE.
Sub-kingdom III. Echinodermata (Gr. edam" hedgehog, and derma, skin; from hav ing a spiny skin). The echinodermata, including the sea-urchins. starfishes, etc., were included ncluded in the sub-kingdom radiata, but they form a very distinct group, and although they have been classified by prof. Huxley, on account of some remarkable affinities with the lower worms, as the tape-worn) and other intestinal parasites, in a sub-kingdom called annuloida, the weight of authority inclines to a separation into a distinct group, constituting a sub-kingdom. The echinodermata may be defined as
follows: Simple marine organisms, the body of the adult more or less conspicuously radiate, that of the young often distinctly bilateral. Nervous system radiate, composed of an msophageal ring and radiating branches. Sexes generally distinct, rarely united. They are commonly known as sea-urchins, star-fishes, brittle stars, feather-stars, sea lilies, sea-cucumbers, etc. The echinodermata are divided into seven orders: Order I. Crinoidea (Gr. krinon, a lily, and eidos, form). Sea-lilies; feather-star (q.v.); medusa-head crinoid; pentacrinus (q.v.); stone-lily—enerinus liNformis. See ENCRI NITES and CRINOIDEA.
Order II. Blastoidea (Gr. blastos, a bud, and eidos, form). These animals are all extinct, and their fossils are found in the paleozoic formations, chiefly in the carbonif erous rocks. The body was fixed to the sea-bottom by a short, jointed pedicel, and in many respects resembled the following.
Order III. Cystoidea (Gr. kystis, a bladder). These organisms are also extinct, and their fossils are confined to the paleozoic age. The body was, in most instances, fixed to the sea-bottom by a short, jointed, calcareous pedicel, and was more or less spherical and covered with numerous polygonal, calcareous plates accurately fitted together. On the upper surface there were two, and sometimes three, apertures, the use of which is a matter of controversy. One was, probably, for the mouth, one for locomotion, and the third for voidiom excreta.
Order IV: OPtiuroidea (Gr. ophis, a snake; aura, a tail; and eidos, form). Sand stars —ophiaria; brittle stars—ophiocoma.
Order V. Asteroidea (star-formed) Star-fishes (q.v.); cross-fish—uraster; sun-star oolaster • eusion-star—gordaster.