A treatise on zoology . lto the sea-floor. Themouth (0) was anteriorand ventral; the anus (As) posterior or postero-ventral. Thetwo were joined by an uncoiled gut, perhaps with a stomachalenlargement in the middle. On either side of this lay the coelom,formed by constriction from the larval stomach or archenteron, inother words, an enterocoel ; it was divided into a right and leftanterior portion (), and a right and left posterior portion { ). Each anterior vesicle was connected with the exteriorby a canal, opening at a dorsal pore (il/) on each side the medianline, sometimes, p
A treatise on zoology . lto the sea-floor. Themouth (0) was anteriorand ventral; the anus (As) posterior or postero-ventral. Thetwo were joined by an uncoiled gut, perhaps with a stomachalenlargement in the middle. On either side of this lay the coelom,formed by constriction from the larval stomach or archenteron, inother words, an enterocoel ; it was divided into a right and leftanterior portion (), and a right and left posterior portion { ). Each anterior vesicle was connected with the exteriorby a canal, opening at a dorsal pore (il/) on each side the medianline, sometimes, perhaps, fusing into one. These canals were in-directly connected () with posterior offshoots from the anteriorcoelom, the right and left hydrocoels ( and ). Gonadsdeveloped from the coelomic endothelium. The ectodermalepithelium was probably ciliated, and a portion of it in the pre-oral lobe () was differentiated as a sense organ, with longercilia and underlying nerve-centre («), from which two gangliated. Fuj. II. Dijdeurvla larvno Hfcn frinu right Ri<l« (i)artly iiftur I^ngX 1, riuteitf of Efhinoid :2, AuTicnlitria of Holothuriiiii ; ;i, lUinnrmriii of Asteroid; 4, Tiyrnaria of Eiiterojmoustnn ;O, month ; , uiiiih ; s, si)iriile ; h;), neural piiilewith eiliii. The strong black lines npre-HMif, cilintid bandH ; the shaded show the course of llio gut. nerves niii ))ack below the ventral surface. In the mesoblasticconnective tissue, derived by the migration of cells, there was atondoncy to the secretion of crystalline calcium carbonate. Except ECHINODERMA—GENERAL DESCRIPTION 5 for the latter character, the Dipleurula agrees in essentials withthe larva of Entcro})neusta, which was described by Joh. Miiller(1850) as an Echinoderm larva, under the name Tornaria(Fig. II. 4). The simplest larval form among recent Echinoderms, that ofthe Holothurians, known as Auricularia (Fig. II. 2, and Fig. III.),differs from the Dipleurula in being bent upon its ve
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Keywords: ., bookcentury1900, bookdecade1900, bookpublishe, booksubjectzoology
