MELOCRINID&®. 301 
rows of 2, 3,5, and three plates, which meet the interambulacrals. Anal 
interradius a little wider, with three plates in the second row, and four in 
the third. Ventral disk low, irregularly convex; the ambulacral spaces 
slightly elevated; the plates —orals included — almost of uniform size. 
Anus subcentral; at the end of a tube. 
Horizon and Locality.— Niagara group; near Louisville, Ky., and St. 
Paul, Ind. 
Types in the collection of Wachsmuth and Springer. 
Remarks. — This form was regarded by Roemer®* as specifically identical 
with his Cytocrinus levis, which comes from the same horizon in Tennessee, 
and resembles it in general form; but the arm trunks of that species are 
composed of single joints, and it has a smaller number of interbrachials. 
Melocrinus Roemeri W. and Sp. (nov. spec.). 
Plate XXII. Figs. 11a, 6. 
Syn. Cytocrinus levis — Roemer; 1860. Silur. Fauna West. Tenn., p. 46, Plate 4, Figs. 2a, 4, c. 
Syn. Crenocrinus levis —Suvumarp; 1866. Trans. Acad. Sci. St. Louis, p. 361. 
Syn. Melocrinus levis (not Goldf.) — W. and Sp. (in part); 1881. Revision Paleocr. Part IL, p. 122. 
Calyx moderately small, turbinate ; dorsal cup about as wide as high, 
gradually spreading to the arm bases, which are formed into five very con- 
spicuous lobes, giving to the calyx, as seen from above, a decidedly stellate 
outline. Plates without ornamentation, a little concave, except the median 
line of the radial plates, which is obtusely angular. The radial appendages 
from which the arms are given off composed of a single series of plates. 
Basals rather large, subequal, forming a shallow cup, which is slightly 
truncate at the lower end. Radials twice as large as the first costals, hexa- 
gonal, about as wide as long; their upper sloping faces a little larger than 
the corresponding lower ones. Second costals very small and curved like 
arm plates; their upper sloping faces unequal, that toward the outer side of 
the ray much the longest, and supporting a distichal, the inner one the first 
arm plate. The trunks, which consist of a single series of plates, give off the 
arms at intervals from alternate sides, not from opposite plates as in species 
with a double series. Interbrachial spaces wide, the first plate large, succeeded 
by two rows of two and three plates respectively, which are followed by disk 
plates. The two outer plates of the upper row curve outward and form the 
sides of the lobes. At the anal side the first plate is larger, and followed by 
* Silur. Fauna West. Tennessee, 1860, p. 48. 
