80 



Cincinnati Society of Natural History. 



Basal plates of moderate size, and regularly pentagonal. Subradials 

 a little more than twice the size of the basals, and those on the pos- 

 terior side hexagonal. First radials about the size of the subradials, 

 pentagonal, prominent, and arcuate on the upper face for the reception 

 of the succeeding plates of the free arms. The free arms bifurcate on 

 the third plate from the first radial, and again on the third or fourth 

 succeeding plate, and again at about the same distance, above this, 

 more plates intervene between the bifurcations, but the divisions con- 

 tinue until, as shown in our specimen, there are three hundred and 

 twenty arms. The arms are long, round, slender, and diminish only 

 slightly in size following each division. The ventral sac or proboscis is 

 very long, extending quite to the extremit}' of the arms, and composed 

 of hexagonal plates pierced by numerous fissures in the sutures. 



This is a very beautiful species from the Keokuk Group, at Craw- 

 fordsville, Indiana, and belongs to the magnificent collection of I. H. 

 Harris, Esq., of Waynesville, Ohio. 



Glyptocrinus pattersoni, n. sp. 



Plate III , figs. 2, and 2a, natural size, both specimens are injured in the interradial 

 areas, but the plates of the radial series are not correctly represented in either figure. 



Calyx small, height and width subequal, with interradial areas de- 

 pressed, so as to give it strong, angular outlines corresponding with the 

 radial series. Surface finely sculptured. 



Basals small, but projecting up between the under sloping sides of 

 the first primary radials. The first radials are the larger plates of the 

 body, hexagonal, and about as long as wide. The strong radial ridge 

 in its extension below, divides at the centre of this plate. The second 

 radials are much smaller than the first, about as high as wide, and 

 hexagonal or heptagonal. The third radials are about the same size 

 as the second. 



The secondary radials arise upon the upper sloping sides of the 

 latter, and become free arms at the third plate without another bi- 

 furcation. 



Arms only ten, and after they become free, at the third plate above 

 the first radial series, consist of strong cuneiform plates, each of which 

 bears a coarse pinnule. They are long, and with their coarse and 

 numerous pinnules form a large, brush} 7 head, with a small calyx. 



The column is round, of medium size, and composed near the head of 

 alternately thicker and thinner plates. 



This species is distinguished b} T the depressed interradial areas by 



