MELOCRINID^. 301 



rows of 2, 3, 3, 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 3 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. 



2'ypes in the collection of Wachsmuth and Springer. 



Remarks. — This form was regarded by Eoemer * as specifically identical 

 with his Cytocrinus l(Bvis, 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, h. 



Syn. Gytocrinm lavis — Roemer; 1860. Silur. Fauna West. Tenn., p. 46, Plate 4, Eigs. la, b, c. 



Syn. Ctenocrinus Icevis — Sfumaed ; 1866. Trans. Acad. Sci. St. Louis, p. 361. 



Syn. Melocrinus Icevis (not Goldf.) — W. and Sp. (in part); 1881. Revision PalcTOcr. Part XL, p. 123. 



Calyx moderately small, turbinate ; dorsal cup about as Avide as high, 

 gradually spreading to the arm bases, which are formed into ^mq 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. Eadials 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. Pauna West. Tennessee, 1860, p. 48. 



