302 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
three plates in the second row, and four in the third. Ventral disk depressed, 
pentagonal; the ambulacral regions slightly raised above the general level ; 
the plates without ornamentation, almost flat, and the sutures difficult to see. 
The disk ambulacra are completely subtegminal; the orals apparently 
unrepresented, and the anus is at the end of a large tube, which bends 
toward the posterior side. 
Horizon and Locality. — Niagara group; associated with Astrwospongia 
meniscus. Decatur Co., Tenn. 
Type in the collection of Wachsmuth and Springer. 
Remarks. — Roemer described this species as Cytocrinus levis, making it 
the type of a new genus. He supposed it had three basals, and he did not 
understand its arm structure, which is evidently that of MJelocrinus. We 
refer the species to the latter genus, but are compelled to change the specific 
name, as Goldfuss in 1826 described a Melocrinus levis from the Eifel, and 
propose for it Melocrinus Roemeri. Roemer originally included in his species 
two forms, the typical one from the Niagara group of Western Tennessee, 
and another from the same horizon of near Louisville. The latter has been 
described by us as Melocrinus oblongus. The two species resemble each other 
in form, but JL oblongus is considerably larger, the calyx contains many more 
plates, and the radial appendages are composed of two rows of brachials in 
place of one. 
Melocrinus obconicus Hatt. 
Plate XXII. Figs. 10a, b, ec. 
1863. Melocrinus obconicus —Haw.; Trans. Alb. Inst., p. 206. 
1875. Melocrinus obconicus — Hatt; 28th Rep. N. Y. State Mus. Nat. Hist., p. 138, Plate 14, Figs. 11-14. 
1881. Melocrinus obconicus — Hat1; 11th Aun. Rep. Geol. Ind. by Collet, p. 269, Plate 13, Fgs. 11-14. 
1881. Mariacrinus obconicus —W. and Sp.; Revision Paleoer., Part II., p. 116. 
Of medium size. Calyx obconical, about as wide as high; gradually 
expanding from the top of the basals to the bases of the free appendages, 
where it is distinctly lobed. Plates covered by numerous radiating ridges, 
which pass out from the middle of the plates to the sides and angles, meet- 
ing those of adjoining plates; the ridges passing up and down the radial 
plates wider and somewhat higher. Besides these ridges the whole surface 
of the plates — that of the ridges included — is finely corrugated, which adds 
greatly to the beauty of the species. 
Basals projecting, forming a short, indistinctly quadrangular, almost cylin- 
drical cup. Radials and costals of about equal size, and all nearly as long 
