PLATYCRINID ZA. He Gilk 
CO. inflatus, C. levis, C. magnificus, C. pentagonalis, C’. roseeformis, C. stellatus, 
and C. striatus, — all from Decatur Co., Western Tennessee — which in all 
probability are mere varieties of Marsupiocrinus tennesseensis (Roemer). A 
fizure of the ventral side of MW. depressus Ang., from the Upper Silurian ot 
Gotland, Sweden, is given on Plate II1., Fig. 23. 
Marsupiocrinus tennesseensis (Rormer). : 3 
Plate LX XV. Figs. 16a, b. | 
1860. Platycrinus tennesseensis —RonmeER; Silur. Fauna West. Tenn., p. 35, Plate 3, Figs. 4a, 4, «, 
1881. ee tennesseensis — W. and Sr.; Revision., Part IL, p. 65 (Proceed. Acad. Nat. Sci. 
Phila., p. 239). 
A rather large species. Calyx greatly depressed, its width about twice | 
its height, the latter equally divided between cup and tegmen. Dorsal cup _ 
saucer-shaped, the base flat, the sides slightly convex, rapidly spreading. ’ 
Plates moderately thin and flat, the ornamentation somewhat variable. In 
the majority of specimens the surface of the plates densely covered with 
somewhat irregular, very fine, closely arranged, longitudinal and transverse 
striee ; the longitudinal ones running in almost parallel lines from the upper 
edges of the radials to the foot of the basals; the transverse ones, which are 
restricted to the lateral margins of the radials, traverse the sutures, and meet 
the longitudinal ones at an angle; the successive angles, as they follow the 
plates, forming an oblique line from the top of the radials to their lower 
angles. In other specimens the striz are broken up into rows of small 
nodes, some of which are round, but most of them elongate, giving to the 
surface a peculiar rugose appearance. Sutures not grooved, and often 
difficult to see. 
Basals spreading horizontally, forming a flat, sharply pentangular disk ; 
the column facet surrounded by a small, circular ridge, and the space within 
slightly excavated; the axial canal rather large and pentagonal. Radials 
hexagonal ; greatest width to length as seven to four, rapidly spreading to 
two thirds their height, the upper faces almost straight, beg but very 
slightly indented for the reception of the costals; the sloping upper faces 
forming a deep notch with corresponding faces of adjoining plates. Costals 
extremely small even for the genus, trigonal, a little wider than long. 
Distichals two, quite unlike in form and size; the first rather large and sub- 
lunate, one of its sides abutting against the costals and meeting above with 
