. The Danish Ingolf-Expedition. Scientific expeditions; Arctic Ocean. 64 PORIFERA. two "roups: the dermal spicules tornota 0-32?—o-53""" ; microsclera ckelce arena fa- of a curious, broad and fat shape, 0-032—0-035""". Of this species we have one specimen, growing on a shell-fragment of a Pecten; the specimen grows on both sides of the shell having grown round the edge from one side to the other; the largest extent of the specimen is i5mm, and the thickness abont 05mm. The colour (in spirit) is brownish yellow. The surface is hispid from projecting derm
. The Danish Ingolf-Expedition. Scientific expeditions; Arctic Ocean. 64 PORIFERA. two "roups: the dermal spicules tornota 0-32?—o-53""" ; microsclera ckelce arena fa- of a curious, broad and fat shape, 0-032—0-035""". Of this species we have one specimen, growing on a shell-fragment of a Pecten; the specimen grows on both sides of the shell having grown round the edge from one side to the other; the largest extent of the specimen is i5mm, and the thickness abont 05mm. The colour (in spirit) is brownish yellow. The surface is hispid from projecting dermal spicules. The dermal membrane is a thin film, but it is wanting to a great extent on the specimen. Oscula and pores were not observed. The skeleton. The dermal skeleton; the dermal spicules form bundles or fibres which stretch from the main skeleton, often from the lower part of this or quite from the base, in an oblique direction up to the surface, and project beyond this, and it is thus chiefly these spicules which cause the hispidity of the surface; outermost the spicules in the bundles are spread out somewhat fan-like. When the sponge is examined from above with a good lens, therefore, the fan-like bundles of dermal spicules are seen. In the membrane chelse are found, but they are very scattered. The main skeleton is of the typical construction, consisting of vertical acanthostyli with their heads fixed on the substratum; the longest of them project beyond the surface and contribute to the hispidity of the sponge. At the base spongin is found, but only to a very slight degree. Spicula: a. Megasclera. 1. The skeletal spicules are acanthostyli;" they are straight or somewhat curved; the head-end is a little swollen, and they taper evenly into a long, fine apex. The spinulation is somewhat strong, the spines on the shaft are compressed and reclined downwards; the spines on the head-swelling are considerably longer, they are not compressed, and radiate straight out;
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectscienti, bookyear1910
