Description of Twelve New Fossil Species. 113 



covered upon the cylindrical surface with irregular and inconstant 

 elevated lines, varj-ing in their course from longitudinal with the steni, 

 to diagonally radiating from a central line. 



If the stem was originally cylindrical, one half of it seems to have 

 been invariably destroj-ed in the rock, so as to leave a flat under surface. 



The greater diameter is generally about an inch. No bifurcation 

 has been observed. 



Collected in the Hudson River Group at Cincinnati. The specimens 

 illustrated are from my own collection, but specimens equally distinct 

 are in the hands of other collectors. It is not common, but it is more 

 abundant than either T. Imosum or T. sulcatum. 



PiSOCRINUS GEMMIFORMIS, U. Sp. 



Plate IX., fig. 6, basal view, natural size. 



fig. 6a, basal view, magnified two diameterS;___,^Xr' 



fig. 6b, side view, showing the hexagonal plate of the calyx. 



fig. 6c, magnified side view, showingTIie hexagonal plate of the calyx. 



The body is small, round, smooth, and possessed of a deep circular 

 cavity, at the base, for the reception of the columnar attachment, 

 which somewhat resembles a bell-mouth. 



The five basal plates united, form a triangle almost equilateral. The 

 three plates, in the angles of this triangle, have, each four sides; the 

 other two plates have three sides each. The two plates, in the angles 

 of the triangular figure, which are not separated, b}^ a triangular plate, 

 are the larger plates, and of equal size. The two triangular plates are 

 the smaller plates and of equal size. In thus describing the plates, I 

 have treated them, as if they each presented an angular point, at the 

 union, with the central part of thecolumn; but this is not strictly true, 

 for a small foramen connects the bod}', with the central opening of 

 the column, and each plate abuts upon this foramen, which gives to 

 each plate an additional i^ide, though a very minute one. 



The five basal plates are succeeded, by three comparatively large 

 plates, which form the principal part of the calyx. Two of these 

 plates are radials, the third is separated from the arras by two small 

 intervening plates. One of these large radials is supported, upon two 

 basal plates; unites two sides, with the adjoining plates of the calyx; 

 supports upon two upper sloping sides, two of the smaller radials; and 

 upon its upper face an arm; making an heptagonal plate. The 

 other large radial has the same form, except that it is supported, upon 

 three basal plates, and is therefore octagonal. The third plate, forming 

 the calyx, is supported, upon three basal plates: unites two sides, 

 with the adjoining plates of the calyx; and suppoits upon its two 



