. Bulletin. Natural history; Natuurlijke historie. DESCRIPTION OF GENERA AND SPECIES 81 Genus Botryocrinus Angelin, 1878 Botryocrinus tenuidactylus Springer Botryocrinus tenuidactylus Springer, 1926B (p. 137, pi 31, fig. 9). Distribution. Springer cites, "Beech River formation; Decatur County, Ten- ; No specimens in the present collections. Class CYSTOIDEA Order RHOMBIFERA Genus Tetracystis Schuchert, 1904 Tetracystis bifarius Amsden, n. sp. Plate XII, figs. 1-4; Text fig. 28 DEScaiEPTiON. Calyx subprismatic; subquadrate in cross section with ambulacral grooves at the angles.
. Bulletin. Natural history; Natuurlijke historie. DESCRIPTION OF GENERA AND SPECIES 81 Genus Botryocrinus Angelin, 1878 Botryocrinus tenuidactylus Springer Botryocrinus tenuidactylus Springer, 1926B (p. 137, pi 31, fig. 9). Distribution. Springer cites, "Beech River formation; Decatur County, Ten- ; No specimens in the present collections. Class CYSTOIDEA Order RHOMBIFERA Genus Tetracystis Schuchert, 1904 Tetracystis bifarius Amsden, n. sp. Plate XII, figs. 1-4; Text fig. 28 DEScaiEPTiON. Calyx subprismatic; subquadrate in cross section with ambulacral grooves at the angles. Calyx plates 23 in number, arranged as shown in figure 28. The food grooves lead right and left from the mouth and branch shortly to form. fi)(lM::} Figure 28. Plate arrangement in Tetracys- tis bifarius. Dashed lines are inferred. System of numbering after Schuchert (1904, p. 219, fig. 26). four that run nearly straight down over the sides of the calyx, reaching almost to its base (pi. XII, figs. 3, 4). Each of these grooves is paved with a row of about 15 short, wide plates. At the upper edge of each of these plates is a small pit, prob- ably indicating the facet to which a brachiole was attached. These alternate in position, being on the right edge of one plate and the left edge of the next. Each of these pits is joined to the main food groove by a short branch. In the posterior interray and about one-fourth the height of the calyx below its summit there is a relatively large, round anal opening (if anal plates were present they have been lost). There are but two pore rhombs, one near the summit of both right and left interrays. The left appears to have 8 and the right 10 hydrospire folds. Between the mouth and the left pore rhomb there is a crescent-shaped opening (madre- porite?), convex orad and having a slightly raised rim. The lower margin of the basal plates is expanded to form an angular flange. Please note that these images are extracted from scanned page images that
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Keywords: ., bookcentury1900, bookcollectionbiodiv, booksubjectnaturalhistory
