144 PROCEEDINGS OF THE ACADEMY OF 



ScAPHiocRiNus DELiCATUS, M. and W. 



Body very small, somewhat cup-shaped, once and a half as wide as the 

 height to the top of the first radials ; sides expanding rapidly upward from 

 about the middle of the subradials to the top of the first radial pieces, and 

 rounding under to the column below. Base very small, and nearly hidden by 

 the column, pentagonal in general outline. Basal pieces merely appearing as 

 minute trigonal facets around the top of the column, and curving upward a 

 little at the extremity. Subradial pieces of comparatively rather large size, 

 three or four of them hexagonal (counting a very obtuse angle at the middle 

 of the under side), and one or two heptagonal. First radial pieces of about 

 the size of the subradials, but shorter and wider, and all pentagonal in form; 

 facet of each for the reception of the second radials not occupying the entire 

 breadth above, and sloping outward. Second radials full twice as long as 

 wide, measuring the breadth at the widest part of the lower end; slender and 

 rounded in the middle, and enlarged at the ends, particularly below; each sup- 

 porting two arms on their upper sloping sides. 



Anal plates arranged in a double alternating series, exactly as in the last 

 described species. Arms slender, rounded, and composed of joints, the lower 

 of which are about twice as long as wide, but those above gradually growing 

 shorter, until they become scarcely longer than wide, on the longer side ; and 

 owing to their oblique arrangement and projections for the support of the 

 pinnulas, presenting a zigzag appearance. At least one of the posterior arms 

 seen to bifurcate on the seventh piece. Pinnulse rounded, comparatively 

 rather stout, composed of joints two or three times as long as wide, and owing 

 to the length of the arm-pieces, widely separated from each other. Column 

 of moderate thickness, and apparently showing a tendency to assume a penta- 

 gonal outline near the base. 



Height of body to the top of first radial pieces, 0-10 inch ; breadth of do. 

 0-15 inch ; length of arms about 0-75 inch. 



This very delicate little species is nearest like that we have already described 

 under the name (S. nanus, but will be readily distinguished by its mucli more 

 slender second radial pieces and arms. This narrowness of the second radials 

 causes the intervening spaces to be wider than the second radial pieces them- 

 selves ; while in the i'. nanus these pieces are so wide as to be in contact with 

 each other all around, excepting on the anal side. These differences give to 

 each of these two forms more strongly marked distinctive features than would 

 probably be apparent from merely reading the descriptions without seeing the 

 fossils themselves. 



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

 ton, Iowa. Lower Carboniferous. No. 297 of Mr. Wachsmuth's collection. 



ScAPHiocRiNus Clio, M. and W. 



Body inversely subcampanulate, somewhat truncated or more or less 

 rounded to the column below, and a little expanded at the top of the first radials, 

 where it is nearly twice as wide as high. Base very small, or almost entirely 

 hidden by the column, not projecting below the horizon of the next range of 

 pieces. Sabradial pieces slightly tumid, and owing to the small size of the 

 base forming most of the under side, as well as half of the height of the body, a 

 little longer than wide, and all (excepting probably one or two not seen on the 

 anal side) presenting a general pentagonal outline, there being no visible angle 

 at the middle of the under side in any of them. First radials larger than the 

 subradials, wider than long, pentagonal in form, and rounded or convex on the 

 outer side above. Second radials short, transverely oblong, or about twice as 

 wide as long, and all rounded on the outer side. Third radials (in four of the 

 rays seen) somewhat longer than the second, pentagonal in form, but with 

 their lateral margins so short as to appear nearly trigonal; supporting the 

 arms on their superior sloping sides. Anal pieces unknown. 



[July, 



