448 



REMARKS ON NEW SPECIES OF CRINOIDEA, 



Size of Specimen. 



Diameter across at the base of free arms, 

 Height (approximately), 

 Height to summit of first radials, 

 Diameter at summit of first radials, . 

 Height of dome above free arms (?), . 



Fragment, Different Specimen. 



Height to summit of first radials, 

 Diameter at summit of first radials, . 



INCIIKK. 



5.50 

 2.08 

 .00 

 1.30 

 2.00 



INCH ICS. 



2.50 

 2.39 



Locality. — Lower crinoid bed, Palls of the Ohio, Clark County, Indiana, one mile below Jeffer- 

 sonville. 



Hadrocrinus DISCUS, n. 8. 

 PL XXVI, Fig. a. 

 Our specimen is slightly crushed, but it is manifest that it was low and flat, as the 

 crushing to which it has been subjected has not fractured the plates, and only slightly 

 opened the sutures, where they were united one to another. It was found in place in the 

 rocks, resting on the base, the upper part of the calyx breaking out slightly rounded or 

 nearly level. The general form is that of a flattish dish, to the second bifurcation of the 

 radial pieces, from which it rises rapidly upward and outward the length of two radials, 

 when it again expands more rapidly. The basal pit is excavate, but in our specimen the 

 basal and first radials only are included in it. The second radials of the first series, and 

 the other pieces connected with the first radials, are slightly pressed upward. This is 

 probably due to the pressure to which it had been subjected. The specimen had lost the 

 covering above the arms. All observed fragments of this species showing any part of the 

 dome covering, arc flattened. The precise form above the arms is unknown. The amount 

 of displacement of the pieces in our specimen, is proof that it was very slightly convex. 

 The base is hidden under the first radials and the remains of the column, and arc relatively 

 smaller than those of H. plenissimus. The first radials, five in number, are nearly of the 

 same size and form: hexagonal, squarely truncated above; on the square summit rest five 

 radials of the first series ; four are pentangular, the fifth piece is hexagonal. These pieces 

 arc cuneiform above, and support two radials cacb, of the second series, upon their upper 

 oblique margins. The hexagonal second radial of the first scries also supports, on its 

 sixth side, one of the interradial pieces. The first radials of the first division vary greatly 

 in size and form ; they are also much larger than the second piece of the first radials im- 



