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Streblacantha circumtexta Jørgensen, 1900

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Streblacantha circumtexta:
This is also a very difficult form to define, and I have not yet succeeded in getting a clear insight into its structure. It can, however, not belong to the genus Sorolarcus HCK., as I at first thought.

There appear to be about 12 strong radial spine, of the same shape as those of Phorticium pylonium CL., but protruding much further. They are more or less round, not three edged.

The outline of the shell in most positions is a broad oval, in a few, almost round. Some optical sections show inner spirals, then a double spiral as in Larcospira minor, other sections show at least 3 shells one outside the other; perhaps with several chambers (only, indistinctly seen).

On the smaller and simpler forms (cfr. Pl. XI, f. 46, c, d; pl. XII, fi. 46 k, l), which I have taken to be specimens in an early stage of development, a single central chamber and spiral twists, which appear to form a snail spiral, may be seen.

On the whole it seems to me at present, that this species may best be placed in the genus Streblacantha HCK., though it may prove not to belong to this genus either.

The outer shell shows a more or less irregular structure and very uneven pores, from rather small to large ones and large holes. On the outside of larger (more developed) forms there are also more or less well developed byspines, very various as regards length and development, from small subulate ones with a rather wide base, to long, narrow needles. When more developed, these byspines are more or less connected through fine branches to an outer, spongy case immediately outside the outer shell. This spongy case is, however, rarely much developed, and seems then to be confined to – or at any rate most developed at – the one end of the shell. Cfr. Also Jörgensen (1900).

Rare, and generally only singly, the small, younger individuals rather more frequent: The Vest Fiord I, 13/1, 0-180m; Henningsvær, 17/1, 0-180m; the sea off Gaukværö, 19/1, 0-700m; Skroven, 1/2, 0-300m; 4/2, 350-300m; 4/4, 0-150m; The Raftsund, 3/2, 0-260m; The Tys Fiord I, 28/3, 0-700m.
Jørgensen 1905











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