The porifera and coelentera . ig. cispera H., natural size. stalked cup, with a thick body wall, formed as above described,by folding and coalescence. Further growth of the body wallcauses it to be thrown into numerous folds, the edges of Avhichrepresent the greatly extended oscular margin. Another Hetero-coele sponge of aberrant form, requiring no explanation, is EilhardiaSchulzci (Fig. 13). It is evident from the instances that have been adduced, thatthe changes in the form of the sponge person which result simi)lyfrom an uneven or local expansion of the surface of the body wall
The porifera and coelentera . ig. cispera H., natural size. stalked cup, with a thick body wall, formed as above described,by folding and coalescence. Further growth of the body wallcauses it to be thrown into numerous folds, the edges of Avhichrepresent the greatly extended oscular margin. Another Hetero-coele sponge of aberrant form, requiring no explanation, is EilhardiaSchulzci (Fig. 13). It is evident from the instances that have been adduced, thatthe changes in the form of the sponge person which result simi)lyfrom an uneven or local expansion of the surface of the body wall,are numerous and often complicated, but may, however, result in asimple thickening of the body, and a consequent retention of, andreversion to, the primitive form. As a result of a disproportionate increase in the thickness of lO SPONGES the body wall the primitive vase-like sponge person may assumea more massive form, and in the simplest cases becomes barrel-shaped (Fig. 16) or globular (Fig. 30), according to the degree of. Fio. Schuhei, Pol. (After PoU-jaeff, Challenger Reports.) Natural size. thickening. If the growth predominates at the base of the spongeit acquires the shape of a shallow cone or volcano, the crater beingrepresented by the osculum, and in such forms the vertical height
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Keywords: ., bookcentury1900, bookdecade1900, booksubje, booksubjectctenophora
