Bulletin Volume 189

 
9781236774958: Bulletin Volume 189

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1916 edition. Excerpt: ...shows how this Conularia-sculpture can be readily derived from that of Serpulites. Its sculpture consists mainly of "sharply undulating transverse striae" (Hall), which well compare with the growth-lines or transverse wrinkles of Serpulites, and it can be readily seen how the acute points of the angular wrinkles may develop into the longitudinal lines. A further very important connecting character is the composition of the tests in both Conularia and Serpulites, of phosphate of calcium and chitinoid substance. Serpulites is typically sessile; that also Conularia was sessile, at least at times, is no more doubted. Besides the early stages of Conularia gracilis showing fixation, Miss Slater has also described a sessile Conularia1 and the writer has seen in the collection of Mr Frederick Braun of Brooklyn a large slab with a number of large Conularias from the western Carboniferous, all of which are sessile, forming a radiating group. Most Conularias, however, detached themselves later and must have become freeswimming. If we finally add that the two marginal thickenings of Serpulites are in structure comparable to the thickened grooves of Conularia, it will be seen that there are enough data to suggest that Conularia may well be a further peculiar development of an annelid of the structure of Serpulites, perhaps largely adapted to swimming. The following. species of Serpulites are before the writer: 1 Serpulites interrogans nov. Plate 29, figures I and 2 The oldest Serpulites before us was collected by the writer in the lowest zone of the Deep Kill graptolite shale (Tetragraptus zone) and is of Beekmantown age. The tubes are small, about 20 mm long, slender and slowly expanding (from.5 mm to 1.7 mm+ in length of 20 mm), strongly...

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