. The animal kingdom : arranged after its organization; forming a natural history of animals, and an introduction to comparative anatomy. Zoology. Fig. 16.—Alcyonian This division receives its designation from the star-like appearance of the short thick tentacula, six or eight in number, when expanded around the mouth. These tentacula are unpro- vided with cilia ; but a number of little projections may be seen along their margins, which probably increase their prehensile power. The mouth leads to a stomach, which is suspended in the midst of the general cavity of the body by partition
. The animal kingdom : arranged after its organization; forming a natural history of animals, and an introduction to comparative anatomy. Zoology. Fig. 16.—Alcyonian This division receives its designation from the star-like appearance of the short thick tentacula, six or eight in number, when expanded around the mouth. These tentacula are unpro- vided with cilia ; but a number of little projections may be seen along their margins, which probably increase their prehensile power. The mouth leads to a stomach, which is suspended in the midst of the general cavity of the body by partitions radiating from its walls ; the number of these partitions, and consequently that of the chambers surrounding the stomach, boing the same with that of the tentacula. Instead of being closed at its lower extremity, however, like that of the Actiniform polypes, the stomach of the Alcyonians opens into the canals that ramify through the fleshy mass in which they are imbedded ; the orifice being surrounded by a circular muscle or sphincter, by the actions of which it may be ex- panded or entirely closed. The chambers which surround the stomach communicate above mth the cavity of the tentacula, each of which has a small orifice at its extremity ; whilst below they are continuous with the ramifying canals just mentioned; and the membranous septa which support the stomach do not cease at its lower extremity, but are prolonged downwards as plaits or folds of the lining of these canals, until they gradually disappear. Here, too, the life of the individual polypes is subordinate to that of the general mass ; and it is from the latter that all the extensions of the fabric by gemmation take place. On the other hand, the ova are developed in the substance of the membranous folds, and make their way outwards through the mouth. In this order we find a remarkable diversity in the charac- ter of the polypidom, together with a great general similarity in the structure of the polypes themselve
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Keywords: ., bookauthorwe, bookcentury1800, bookdecade1860, booksubjectzoology
