FROM THE PALAEOZOIC ROCKS OF INDIANA, KENTUCKY AND OHIO. 



459 



pieces indicate that it was covered by small spine-bearing plates. Column round ; formed 

 of disks of unequal size. Near the body they arc arranged by two small and two larger 

 pieces, and by a piece much larger than those above it. This arrangement is repeated 

 seven or eight times in our specimen, with some irregularity in the size and thickness of 

 the pieces. The column is quite large, when compared with the body it supports. Some 

 of the pieces of the body are covered by very fine granules, placed quite close together. 



Size of /Specimen. 



INCHES. 



Length of body to froo rays, . . . ■ 40 



Diameter to summit of first radials, 22 



Length of remains of proboscis, 55 



Diameter of column, largo pieces, 15 



Locality and Geological Position. — Nucloocrinus bed, Falls of the Ohio, near the mill. Fragments 

 are not rare; good specimens very rare. 



The flattened base gives this species the general appearance of Platycrinus. It termin- 

 ates more abruptly at the column than any other Potinocrinus that has come under my 

 observation. 



PLATYCRINUS. Miller, 1821. 



(Wat. Hist. Crinoi.dk a.) 



Platycrinus Leai, n. s.* 



PI XXVI Fiff tr a l 



Body, below the arm-bases, turbinate ; smooth ; slightly expanded at the junction with 

 the column. The centre of the upper margin of the first radials expanded, forming on 

 each, projections like the lip of a pitcher. Basal pieces three, of equal size; pentangular, 

 forming a cup, equally divided at its upper margin into six slightly concave depressions, 

 for the reception of the first radial pieces. First radials, six in number ; subquadrangular ; 

 a little higher than wide ; a slight, but distinctly defined, smooth ridge, occupies the cen- 

 tre of the first radials, extending from the basals to the lip-like projection, on which are 

 placed the second radials. The ridges upon three of the first radial pieces continue 

 downward along sutures, at which the vertical sides of the basals are united to the 

 swollen part of the basal pieces, with which they unite and are lost in it. The second 



8 dedicated to that able and earnest servant of the Natural Sciences, Isaac Lea, 



* This speoies i 

 LL.L., of Philadelphia, Pennsylvania. 



