NATURAL SCIENCES OF PHILADELPHIA. 147 



below the subradials, truncated about three -fourths its breadth by the facet for 

 the attachment of the column. Basal pieces nearly twice as wide as long, and 

 pentagonal in form, but owing to the shortness of the lateral margins appear- 

 ing nearly trigonal. Subradial pieces a little wider than long, three pentago- 

 nal, and two on the anal side hexagonal (without counting a scarcely defined 

 angle at the middle of the under side of each). First radial pieces of about 

 the size of the subradials, generally wider than long, and pentagonal in form. 

 Second radials about as long as wide, distinctly rounded on the dorsal side, 

 and quadrangular in outline. Third radials somewhat larger than the second, 

 more or less expanded at the upper end, and rounded and contracted in the 

 middle ; each bearing two arms on its superior sloping sides. 



Anal plates forming a double alternating series of five or six pieces, as in 

 the last ; the lowest piece resting between the upper sloping sides of two of 

 the subradials, partly under the first radial on the right, and connecting on the 

 left above the middle, with another piece resting upon the upper truncated 

 edge of one of the subradials, and joining the first radial on the left. 



Arms ten, simple from their origin on the third radials, composed of some- 

 what wedged-formed pieces, about as long as wide on the longer side, which 

 projects above, alternately on opposite sides of the arms, for the reception of 

 the pinnuljE, so as to present a somewhat zigzag appearance. Pinnulse stout, 

 arranged at intervals of near their own breadth apart, and composed of joints 

 that are about as long as wide. Surface granular ; bod}' plates even, and merely 

 separated by linear sutures. Column of comparatively moderate size, faintly 

 subpentagonal, near the base, and composed of rather thin, nearly equal plates, 

 with a very small central perforation. 



Height of body to the top of first radial pieces, about 0-12 inch ; breadth, 

 0-20 inch ; length of arms, about 0-75 inch ; thickness of column at base, near 

 0-07 inch. 



This species is related to the last two, but is readily distinguished by the 

 more conical form of its body, produced by the protuberance of its base, as 

 well as by having two arms to each ray all around, instead of only one in the 

 anterior ray. It also differs from both in having its body plates even, instead 

 of very convex, or tumid, as in S. scalaris, or costate, as in S. fiscellus. 



Locality and position. — Lower division of the Burlington group, at Burling- 

 ton, Iowa. Lower Carboniferous. No. 284 of Mr. Wachsmuth's collection. 



ScAPHiocRiNUS N0TABILI3, M. and W. 

 Body large, obconic, or expanding gradually from the column to the middle 

 of the first radials, at which point these pieces are protuberant, so as to give 

 the general outline, (as seen in a side view) a tendency towards an inverted 

 bell-shape. Base of a deep cup form, less than twice as wide at the top as the 

 height, or about one-third as high as the body to the top of the first radials. 

 Basal pieces higher than wide, and pentagonal in form, the lateral margins 

 being longest. Subradial pieces nearly twice as long as the basal, hexagonal 

 in form, excepting the two on the anal side, which are heptagonal. First ra- 

 dials somewhat larger than the subradial pieces, slightly wider than long, 

 pentagonal in form, and each provided with a very profound sinus for the re- 

 ception of the second radials, more than one-third as wide as its upper edge, 

 and extending about halfway down its outer side. Second radial pieces com- 

 paratively very small, or about one-third as large as the first ; pentagonal in 

 form, about as wide as long, rounded on the outer side, and so deeply inserted 

 in the sinus of the first radials on a kind of shoulder-like projection, that their 

 mesial angle above scarcely rises beyond the upper margins of the first radials, 

 each supporting two arms on its superior sloping sides, and separated from 

 that of the next ray on each side, by an interradial space of about one and a 

 half its own breadth. Anal plates two and about half of the third, included as a 

 part of the walls of the body, hexagonal in form, and having the usual arrange- 

 ment of those of Fot&riocrimtes, in a double, vertical, alternating series. 



1869.] 



