Outlines of zoology . Fig. 84.—Diagrams of Types of Alcyonaria.—After Ilickson. Types of Alcyonaria :—I. Of Stolonifera ; II. of Alcyonacea; III. of Axifera;IV. of Stelechotokea. ciliated groove (siphonoglyphe or sulcus) in the stomodaeum i68 PHYLUM CCELENTERA. (ventrally). The mesenteries bear retractor muscles, allsituated on the sulcar aspect (see Fig. 8i), and eachmesentery bears a mesenterial filament. The two dorsal(asulcar) mesenteries are long, ciliated, and non-glandular;they are respiratory in function and cause an upwardcurrent, that in the sulcus being downward. Many _A1-cyonarians
Outlines of zoology . Fig. 84.—Diagrams of Types of Alcyonaria.—After Ilickson. Types of Alcyonaria :—I. Of Stolonifera ; II. of Alcyonacea; III. of Axifera;IV. of Stelechotokea. ciliated groove (siphonoglyphe or sulcus) in the stomodaeum i68 PHYLUM CCELENTERA. (ventrally). The mesenteries bear retractor muscles, allsituated on the sulcar aspect (see Fig. 8i), and eachmesentery bears a mesenterial filament. The two dorsal(asulcar) mesenteries are long, ciliated, and non-glandular;they are respiratory in function and cause an upwardcurrent, that in the sulcus being downward. Many _A1-cyonarians are dimorphic, having in addition to the typicalpolyps {autozooids) dwarf siphonozooids, with suppressed. Fig. 85.—Corallitim rubrum, a corner ofa colony.—After Lacaze-Duthiers. /J., Anthocodia or retractile portion ofa polyp; r.^., com-oletely retracted polyp, with the verruca or calyx portionleft protruding ; C, coenenchyma ; T., pinnate tentacles. tentacles, strongly developed sulcus, no mesenteric fila-ments, and often ill-developed mesenteries. Their functionis to drive currents of water through the canal systems ofthe colony, and they are sometimes reproductive as the exception of one small family of solitary forms(Haimeidae), the Alcyonarians form colonies which are invarious ways supported by spicules, or by spicules and anaxis. The spicules, which take the most diverse forms,seem to be begun at least by ectodermic cells (a pair to ALCYONARIA. _ 169 each spicule), but they usually pass into the nematocysts are usually small. A number of Alcyon-arians are viviparous; the embryo iB usually a planula. Colonies are formed in different ways, (i) A parent pol
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Keywords: ., bookcentury1900, bookdecade1910, bookidcu3192, booksubjectzoology
