The porifera and coelentera . of the latter. (6) Epitheca, anoflset of the basal plate which surrounds the base of the theca ina ring-like manner. (7) /<///, laminae which extend upwards from THE ANTHOZOA 63 the bottom of the calycle and project between the inner edges ofcertain septa and the columella. In addition to these parts, otherstructures are found in the skeletons of certain corals. Dissepi-ments are oblique calcareous partitions stretching from septum toseptum, and closing the interseptal loculi below (see Fig. ). The whole system of dissepiments in any given calyx is oftenc
The porifera and coelentera . of the latter. (6) Epitheca, anoflset of the basal plate which surrounds the base of the theca ina ring-like manner. (7) /<///, laminae which extend upwards from THE ANTHOZOA 63 the bottom of the calycle and project between the inner edges ofcertain septa and the columella. In addition to these parts, otherstructures are found in the skeletons of certain corals. Dissepi-ments are oblique calcareous partitions stretching from septum toseptum, and closing the interseptal loculi below (see Fig. ). The whole system of dissepiments in any given calyx is oftencalled endotheca. Sijnapticula are calcareous bars uniting adjacentsepta (Fig. XXXI. 3). Tabulae are stout horizontal partitionstraversing the whole space within the calycle. Though the skeleton or corallum of the Scleractiniae appearsto lie within the zooid, it is morphologically external to it, as isbest shown by its developmental history, which has been studiedby G. von Koch in Adroides calicularis (55) and in Caryophyllia. y^^^^yi.^, r^ ..... Iiu. XXIX. Radial section of the larva of Astroides calicularis, which has fixed itself on a piece of , ectoderm; en, endodenn; mg, mesogloea; mm, mesenteries; S, septum; li, basal plate,formed of ellipsoids of carbonate of lime secreted by the basal ectoderm ; ep, epitlieca. (AfterG. von Koch.) cyathus (105), and by H. V. Wilson in Manicina areolafa (98).The larvae of Astroides are at first ciliated and free-swimming,and do not acquire a corallum until they fix themselves. Thefirst trace of the corallum appears as a ring-shaped plate of cal-careous tissue situated between the basal ectoderm and the surfaceof attachment. It is composed of calcium carbonate in the formof numerous spheroidal masses of concentric structure, each massbuilt up of numerous rhombic crystals. Von Koch states definitelythat the calcareous nodules are formed as a secretion product ofthe ectoderm, and he gives figures which fully bear out his assertion(Fig.
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Keywords: ., bookcentury1900, bookdecade1900, booksubje, booksubjectctenophora
