DICIIITONIDA. — Family ASCIDIAD/E, E.
Forbes. Synonyms: Tel simples, Savigny ; Ascididcr, MacLeay ; TUllith78 libres ou As cidiens, Lamarck ; Aseidiaria, Stark; " les Iso Cuvier ; Ascidiacea, pars, Blainville ; Ascidiens simples, 11rilne- Edwards ; Ascidiens, Van Beneden.
Body simple, fixed ; animals isolated or gregarious ; not united into groups by a com mon integument; oviparous, not gemmipa rous. The following genera are members of this family : — Genus Ascidia, Baster and Linn/ens. — " Rarely," says Professor E. Forbes, " is the dredge drawn up from any sea bed at all pro lific in submarine creatures, without contain ing few or many irregularly shaped leathery bodies, fixed to sea-weed, rock, or shell, by one extremity or by one side, free at the other, and presenting two more or less pro minent orifices, from which, on the slightest pressure, the sea-water is ejected with great force. On the sea shore, when the tide is out, we find similar bodies attached to the under surface of rough stones. They are variously, often splendidly, coloured ; but otherwise are unattractive, or even repulsive, coasts of the Channel 1- and the Mediterra nean, and in the Chinese Seas, are valued as articles of food In this genus (fig.766.) the body is sessile ; test, coriaceous or gelati nous ; branchial orifice eight and six-lobed ; branchial sac not plicated, surmounted by a circle of simple tentacular filaments.
Genus Molgula, E. Forbes; synonym, As cidia, Auct.—Body more or less globular, attached or free 3: ; test membranous, usually invested with extraneous matter ; orifices on very contractile and naked tubes, the bran chial six-lobed, the anal four-lobed.
Genus Cynthia, Savigny ; synonym, Ascidia, sessile, fixed or unattached; test coriaceous ; branchial and anal orifices open ing in four rays or lobes; branchial sac lon gitudinally plicated, surmounted by a circle of tentacular filaments.
Genus Dendrodoa, Mac Leay.—Body sub cylindrical, fixed, sessile; test coriaceous, Smooth ; orifices terminal, minute, indistinctly quadrifid ; branchial sac plicated ; tentacula in aspect. These creatures are Aseidice, pro
perly so called. Numbers of them are often found clustering among tangles, like bunches of some strange semitransparent fruit." Some species (in France, nulg4 " le vichet ") on the simple (fig. 778). Dendrodoa closely agrees with Cynthia in its branchial reticulations and its digestive apparatus ; but, as Mr. Mac Leay has observed, of the two ovaries possessed by Cynthia, only one, and that the left, is found in Dendrodoa, whilst the right ovary alone is present in Pandocia.
Genus Chelyosoma, Broderip and Sowerby. —Body depressed, oblong, fixed, sessile ; test coriaceous, its upper surface consisting of eight somewhat horny, angular plates ; ori- .
fices small, prominent, perforating the plated surface, each surrounded by six triangular valvules (fig. 767.) ; branchim plicated ; ten tacles simple.
Family CLAVELLINID/E, E. Forbes. Syno nyms : Aseidife, Auct. ; Tethyes simples, pars, Savigny ; Ascidiens sociales, Milne-Edwards ; Perophoriens, Van Beneden.
Body compound, fixed ; animals connected by creeping, tubular prolongations of the com mon tunic, through which the blood circu lates. This family comprises two genera :— Genus Clavellina, Savigny ; synonym, As oldie, Auct.—Body elongated, erect, more or less pedunculated ; test smooth and trans parent ; branchial and anal orifices without rays ; thorax usually marked with coloured lines (fig. 768.).
To the Ascidiader we may provisionally join the following obscure form, occurring on the coasts of South America : Genus Fodia, Bose. — Body oval, mammil lated, divided throughout its length by a vertical partition, which contains the stomach, into two unequal tubes open at each end by an orifice, the superior aperture rather depressed and ir regularly toothed, the inferior bordered by a circular collar forming a sucker, and serving to attach the animal to extraneous objects.