NATURAL SCIENCES OF PHILADELPHIA. 27 



no species liable to be confounded with this when specimens can be seen with 

 its arms well preserved. 



Locality and position. Keokuk division of the Lower Carboniferous series 

 at Crawfordsville, Indiana. The typical specimen belongs to Mr. Corey, of 

 Crawfordsville, to whom we are indebted for the loan of it. 



Scaphiocrinus depressus, M. and W. 



Body small, somewhat basin-shaped, about twice as wide as high to the top 

 of the first radials, broadly truncated and concave below, with but Blightly 

 expanded or nearly vertical sides. Base occupying the concavity of the under 

 side, and apparently flat or concave. First radial pieces about as high as 

 wide, a little convex, rising vertically, except below, where they curve ab- 

 ruptly inwards to connect with the base; all seen, presenting pentagonal gen- 

 eral outlines on their outer faces. First radial pieces nearlv twice as wiife as 

 high, pentagonal in form, and truncated their entire breadth above for the 

 reception of the second radials. Anal pieces unknown. Second radials 

 longer than wide, strongly constricted in the middle with steeply sloping sides 

 for the support of the arms above. Arms simple from their origin on the 

 second radials, slender, and composed of long, rounded, somewhat constricted 

 joints, which are obliquely truncated at the ends, with the upper end of all 

 projecting, alternately on opposite sides for the support of long, very slender 

 tentacles, composed of long joints. 



Breadth of body, near 0-30 inch; height, 0-15 inch. Arms apparently 

 about 1-12 inches in length, and only 0-05 inch in thickness at the constricted 

 part of one of the lower joints; first four joints 0-32 in length. 



In its depressed body, with nearly vertical sides, and broadly truncated, 

 concave lower part, this species seems to resemble S. unicus, of Hall, as near 

 as can be determined from a description alone. It differs, however, in having 

 the arms simple from their origin on the second radials, with long instead of 

 very short joints. It is peculiar iu the broadly truncated and concave char- 

 acter of its under side, as well as in the slenderness of its arms and pinnula;. 

 The latter are also remarkably distant from each other, owing to the length 

 of the arm joints. 



Locality and position. Crawfordsville. Indiana. From the Keokuk division 

 of the Lower Carboniferous series. 



Zeacrinus? armiger. 



Body small and depressed, or nearly basin-shaped, but with the under side 

 rounded, and concave in the middle. Base very small and nearly or quite 

 hidden in the concavity of the- under side. Subradial pieces comparatively 

 large and curving under below, but not tumid or convex; three with a general 

 pentagonal outline, but probably having a sixth obtuse angle at the middle of 

 each below ; the other two, on the anal side, presenting a general hexagonal 

 form, but truncated by the anal pieces in such a manner as to present a hep- 

 tagonal form, exclusive of the very obtuse angle probably existing at the 

 middle of the under side of each. First radial pieces twice as wide as high, 

 pentagonal in form, and truncated across their entire breadth. Second r 

 als as high as wide, each bearing two arms on their superior slopiug sides, 

 and developed into a long, slender, rounded, mucronate spine, which is 

 directed nearly horizontally outward. Anal pieces small, and arrange. 1 in a 

 double alternating series, the first on lowest piece being somewhat cuneiform 

 and wedged obliquely down between one of the subradials and the under 

 of the first radial on the left, so as to touch, by a very short side, the next 

 subradial on the left; second anal piece resting on the short truncated sum- 

 mit of one of the heptagonal subradials, and connecting on the right with 

 one of the first radial pieces, and on the left with one of the upper sidi 

 the first anal piece, and another piece resting on the latter. Above these, 



1870.] 



