156 PROCEEDINGS OF THE ACADEMY OF 



lateral angles slightly truncated, so as to give an obscurely hexagonal or hep- 

 tagonal outline ; all broadly truncated nearly their entire breadtb above, and 

 one on the immediate right of the anal series, resting in part directly upon the 

 upper truncated side of one of the subradials, and elevated almost its entire 

 length above the horizon of those of the other rays. In this latter ray, and 

 the one on the immediate left of the anal series, the second piece is quadran- 

 gular, and wider than long, while the third is pentagonal, and supports the 

 first division of the arms on its superior sloping sides. These divisions in the 

 ray on the right are simple, rounded, and each composed of a single series of 

 somewhat wedge-shaped pieces; while the left branch of the one on the left 

 of the anal series, bifurcates again on the second piece, making three arms in 

 this ray, which are constructed like those already described, and continue 

 simple as far as they can be traced. In the only other ray preserved in the 

 specimen, the bifurcation takes place on the second radial, beyond which the 

 arms continue simple. 



First anal piece nearly as large as one of the first radials, hexagonal, and 

 resting between the upper sloping sides of two of the subradials, partly under 

 the first radial on the right, while it connects on the left with the second anal, 

 and supports a third on its truncated upper side. Second anal piece rather 

 large, longer than wide, hexagonal, and resting upon the superior truncated 

 side of one of the subradials. Third anal piece smaller than the others, hexa- 

 gonal, and surmounted by several other hexagonal pieces in direct succession, 

 belonging to the. proboscis. 



Surface apparently smooth. Columnar facet rather large and marked with 

 distinct radiating stria? around the margins. 



Length of body to summit of first radials, about 0-48, excepting in the ray 

 on the immediate left of the anal series, where it is 0-58 inch; breadth about 

 0-56 inch. Breadth of columnar facet, 0-26 inch. Usual diameter of the arms 

 after the bifurcations, 012 inch. 



Locality and position. Crawfordsville, Indiana. Keokuk division of the 

 Subcarboniferous series. 



POTERIOCRINDS (SCAPHIOCRINUS) TENUIDACTYLUS, M. & W. 



Body in comparison with the length of the arms small, inversely campanu- 

 late below the summit of the first radial pieces ; being narrowly rounded below 

 and rather expanded above, where the breadth is nearly twice the height. 

 Base less than half as wide as high, basin-shaped, the sides rounding under to 

 the columnar facet, which is of medium size and a little concave. Basal 

 pieces well developed, pentagonal, and wider than long. Subradial pieces 

 twice or three times as large as the basal ; those on the anterior side (the only 

 ones seen) hexagonal. First radials wider but shorter than the subradials ; 

 transversely truncated about three-fourths their entire breadth above, for the 

 reception of the succeeding radial pieces ; those on the anterior side curving a 

 little outwards and having an irregular pentagonal outline, the superior lateral 

 angles being more or less truncated, or rounding inwards. Second radials 

 pentagonal, nearly as long as wide, separated by interradial pieces of nearly 

 their own breadtb, rounded and constricted around the middle, with the central 

 superior angle prominent, and the sloping margins on each side of it supporting 

 the arms. 



Anal pieces unknown. Arms long, slender, and in two of the anterior rays 

 known to bifurcate on the tenth piece above the third primary radials, after 

 which they are seen to be extended to a considerable length, without, showing 

 distinctly another division, though there is some appearance of such bifurca- 

 tion in one of the branches, on the twentieth piece. Immediately after the 

 division of the rays on the third primary radials, the arms are rounded and 

 composed of wedge-shaped pieces, wider than long, and alternately thicker 

 and thinner on opposite sides, each one supporting at its larger end a stout 



[Aug. 



