. The Danish Ingolf-Expedition. Scientific expeditions; Arctic Ocean. 96. PORIFERA. III. 41. H. planca n. sp. PI. X, Fig. 1. Incrusting; surface densely hispid. Spicnla: megasclcra; the skeletal spicules acanthostyli with- out a distinct head, divided into two groups, large, only spined at the base, o-jj—o-6j""", small, spined about in the lower half, 0-16—0-27"""; the dermal spicules tylotornota osi—0-29'"'"; microsclera three forms, chela' arcuatce o-oiS—o-o^1/""", sigmata of hvo forms, large, contorted, 0-021—0-028""", sm
. The Danish Ingolf-Expedition. Scientific expeditions; Arctic Ocean. 96. PORIFERA. III. 41. H. planca n. sp. PI. X, Fig. 1. Incrusting; surface densely hispid. Spicnla: megasclcra; the skeletal spicules acanthostyli with- out a distinct head, divided into two groups, large, only spined at the base, o-jj—o-6j""", small, spined about in the lower half, 0-16—0-27"""; the dermal spicules tylotornota osi—0-29'"'"; microsclera three forms, chela' arcuatce o-oiS—o-o^1/""", sigmata of hvo forms, large, contorted, 0-021—0-028""", small, plane, somewhat circularly curved, 0-014""". This species forms incrustations on Brachiopods, shells, Bryozoa and small stones; it reaches a greatest extent of about i5mm, with a thickness of about o-5mra. The colour (in spirit) is white in all specimens. The surface is distinctly and densely hispid. The dermal membrane is very thin and transparent; it is perforated by a multitude of close-lying circular openings of different sizes, which are oscula and pores, but there is no such difference in size between them, that it can be decided therefrom which of them are incurrent and which excurrent openings; the openings are seen only when the sponge is somewhat dried; when lying in spirit close-standing openings of canals are seen to shine through the membrane. The skeleton. The dermal skeleton consists of bundles of dermal spicules, which stretch obliquely from the lower part of the main skeleton up to the dermal membrane; the bundles are small, each not consisting of many spicules; the spicules all have the rounded ends inwards and the points outwards; the spicules in the bundles are a little divergent outwards and bear the dermal membrane, but they do not penetrate through it or only very slightly; as the longest skeletal styli reach the dermal membrane and project through it, the bundles of dermal spicules are thus lying between the ends of the long
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectscienti, bookyear1910
