PLATYCRINTDAE 
6l 
in the matrix and several with arms and stem attached, in none of which is there any trace 
of surface markings. The tendency is toward anchylosis of the basals. Along wdth these 
characters the low and broadly spreading calyx makes the species readily recognized. 
Horizon and locality. Eiicalyptocrinns zone of Beech River formation, Brownsport 
group, Tuck’s Mill, Decatur County, Tennessee. 
Marsipocrinus striatissimus new species 
Plate i8, figs, i-y 
A very large species, attaining a diameter of 50 or 60 mm., with extremely 
thin plates, so that specimens are rarely found nndistorted, or with anything 
but the basal pentagon preserved. Calyx low and broadly spreading, with arm 
facets directed about horizontal. Base convex, with narrow rounded rim about 
column facet. iBr projecting but little, mostly smooth. Tegmen low, usually 
crushed, with plates level, smooth, or covered with small nodes or tubercles; 
ambulacra not conspicuous. Surface of cup marked by an exceedingly fine 
striation, with straight lines crossing the sutures from plate to plate. 
Roemer’s figure 4J may be of this species, and it was also this which Wachsmuth and 
Springer had in mind when in describing their much smaller and more robust M. .striatns 
they stated that it sometimes reached 6 cm. in width. It is not uncommon on the glades as 
fragments only, characterized by large size and the extreme thinness of the plates. The 
crushed specimen figured on plate 18, figures i, la, is the nearest to a complete calyx that is 
known. Two fairly robust dorsal cups have the characteristic delicate striation, while in the 
specimen with arms it is almost obliterated by pressure. 
Horizon and locality. Eucalyptocrinus zone of Beech River formation, Brownsport 
group, Niagara!! ; Tuck’s IMill and glades, Decatur County, Tennessee. 
Marsipocrinus magnificus (Troost) 
Plate ig, figs, i-ib 
Cupellaecrinites magnificus Troost, Proc. Am. Assn. Adv. Sci., 1850, p. 61 (nom. mid.). — Ciipellaecrinus 
magnificus Shumard, Trans. Acad. Sci. St. Louis, 2, 1866, p. 361. — Marsipocrinus magnificus (Troost) 
Wood, Bull. 64, U. S. Nat. Mus., 1909, p. 34, pi. 10, figs. 5-7. 
A very large and robmst species, with four arms to the ray. Calyx bi- 
convex ; height 27 mm. width 40 mm. Base about flat, with a thickened rounded 
rim surrounding the column-facet; basal pentagon about three fifths the diame- 
ter of calyx. Two secundibrachs in succession meet above the triangular primi- 
brach, the second one axillary, follotved by a second division of the ray, giving 
four arm openings instead of two as in all the preceding species. iBr verv large, 
broadly shield-shape, truncate above, and but little projecting. Tegmen com- 
posed of strong convex or nodose plates, with ambulacra not conspicuous. 
Surface of cup deeply sculptured, with beveled sutures, and coarse tubercles 
coalescing into prominent ridges to the corners of the basal pentagon, and 
from there across the radials, forming conspicuous triangles with apex at the 
primibrach. 
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