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SIPUNCULOIDEA

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Originally appearing in Volume V25, Page 151 of the 1911 Encyclopedia Britannica.
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SIPUNCULOIDEA , marine animals of uncertain See also:

affinities, formerly associated with the See also:Echiuroidea (q.v.) in the See also:group See also:Gephyrea. Externally, the See also:body of a Sipunculoid presents no projections: its See also:surface is as a See also:rule even, and often glistening, and the See also:colour varies from whitish through yellow to dark See also:brown. The anterior one-See also:quarter or one-third of the body is capable of being retracted into the See also:remainder, as the tip of a See also:glove-See also:finger may be pushed into the See also:rest, and this retractile See also:part is termed the introvert. At the tip of the introvert the mouth opens, and is surrounded in Sipunculus by a See also:funnel-shaped, ciliated lophophore (See also:figs. 1 and 2). In Phascolosoma and Phascolion this funnel-shaped structure has broken up into a more or less definite group of tentacles, which in Dendrostoma are arranged in four See also:groups. In Aspidosiphon and Physcosoma the tentacles are usually arranged in a See also:horse-See also:shoe, which may be See also:double, overhanging the mouth dorsally. On the surface of the funnel-shaped lophophore are numerous ciliated grooves, and each of the tentacles in the tentaculated forms has a similar groove directed towards the mouth. These grooves doubtless serve to See also:direct currents of See also:water, carrying with them small organisms towards the mouth. The skin consists of a layer of cuticle, easily stripped off, secreted by an ectodermal layer one See also:cell thick. Within this is usually a sheath of connective See also:tissue, which surrounds a layer of circular muscles; the latter may be split up into See also:separate bundles, but more usually See also:form a See also:uniform See also:sheet. Within the circular muscles is a layer of See also:longitudinal muscles, very often broken into bundles, the number of which is often of specific importance.

Oblique muscles sometimes See also:

lie between the circular and longitudinal sheaths. On the inner surface is a layer of peritoneal epithelium, which is frequently ciliated, and at the bases of the retractor muscles is heaped up and modified into the reproductive See also:organs. The ectoderm is in some genera modified to form certain excretory glands, which usually take the form of papillae with an apical opening. These papillae give the surface a roughened aspect; the use of their secretion is unknown. They are best See also:developed in Physcosoma. When the body of a Sipunculoid is opened, it is seen that the body-cavity is spacious and full of a corpusculated fluid, in which the various organs of the body See also:float. The most conspicuous of these is co-educational; founded in 1883), All See also:Saints School (See also:Protestant Episcopal), for girls, and a Lutheran Normal School (1889). The See also:city is the see of a See also:Roman See also:Catholic and of a Protestant Episcopal See also:bishop. The See also:river falls here about zoo ft. in See also:half a mile and provides See also:good water See also:power for manufactures. The See also:total value of the factory products increased from $883,624 in 1900 to 51,897,790 in 1905, or 114.8%. See also:Sioux Falls is a jobbing and wholesaling centre for See also:South Dakota and for the adjacent parts of See also:Iowa and of See also:Minnesota. A See also:quartzite See also:sandstone, commonly known as See also:jasper or " red See also:granite, " is extensively quarried in the vicinity, and See also:cattle raising and farming are important See also:industries of the surrounding See also:country.

A See also:

settlement was made at Sioux Falls in 1856, but this was abandoned about six years later on See also:account of trouble with the See also:Indians. A permanent settlement was established in 1867, and Sioux Falls was incorporated as a See also:village in 1877 and was chartered as a city in 1883.

End of Article: SIPUNCULOIDEA

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