142 PROCEEDINGS OF THE ACADEMY OF 



breadth, as is also the case with all the arm joints. It also differs in having 

 two arms to each ray, all around, instead of only one in the anterior ray, as 

 well as in the number of pieces in each arm below the bifurcations. Its arms 

 are likewise proportionally more slender. 



Locality and position. Lower division of the Burlington group, at Bui-lington, 

 Iowa. Lower Carboniferous. Mr. Wachsmuth's collection. 



ScAPHiocRiNCS STRiATCS, M. and W. 



Body below the top of the first radial pieces subhemispherical, being regu- 

 larly rounded below ; composed of thick plates, which are ornamented with 

 distinct, somewhat broken striae, running vertically, so as to radiate from the 

 base, but all parallel with each other on each individual plate. Basal pieces 

 hidden by the column externally. Subradials about as wide as long, five of 

 them showing a pentagonal outline (there being no visible angle at the middle 

 of their bases on the outside), and one on the anal side hexagonal, the latter 

 being a little larger than the others. First radial pieces slightly shorter than 

 the subradials, but about once and a half as wide, all having a general pentag- 

 onal form, being broadlj'' truncated their entire breadth above, and having the 

 articulating surfaces each marked with two very distinct transverse furrows. 

 First anal piece a little longer than wide, hexagonal in form, and resting upon 

 the truncated upper end of the odd subradial between two of the first radials, 

 beyond which it projects nearly half its length ; truncated above for the recep- 

 tion of a second anal. Other parts unknown. 



Sutures distinctly channelled, so as to impart a moderate convexity to the 

 plates. 



Height to top of first radials, 0-20 inch ; breadth, 0-46 inch. 



This is a typical Scaphiocrinus, as far as its parts are known, and seems to be 

 most nearly related to S. simplex, of Hall, from which it may be at once distin- 

 guished, however, by its channelled sutures, convex plates and peculiar sculp- 

 turing. 



Locality and position. Lower Burlington beds, of the Lower Carboniferous, 

 at Burlington, Iowa. No. 274 of Mr. Wachsmuth's collection. 



Scaphiocrinus penicillus, M. and AV. 



Body small, somewhat basin shaped, or about three times as wide as the 

 height to the top of the first radial pieces, truncated and a little concave below. 

 Base very small, and nearly or quite hidden by ths column in the shallow con- 

 cavity of the under side. Subradials generally wider than long, with a pen- 

 tagonal outline, excepting one on the anal side, which has the upper angle a 

 little truncated, so as to make a sixth angle ; there is doubtless also another 

 obtuse angle at the middle of the lower side of each, covered by the column. 

 First radial pieces wider than high and pentagonal in form. Second radial 

 pieces nearly twice as long as wide, expanded at each end, and distinctly con- 

 stricted along the middle, where they are each somewhat carinated on the dor- 

 sal side ; all pentagonal in form and supporting each two arms on their sujje- 

 rior sloping sides, excepting in the anterior ray, where this piece is quadran- 

 gular and supports but one arm. 



First anal piece wedged obliquelj'^ down in between two of the subradials, 

 under one side of the first radial, on its right, and connecting by its left side, 

 above the middle, with another anal resting on a very short truncated side of 

 one of the subradials, and connecting on the left with the first radial of that 

 side. Above these one or two other pieces are seen between the arms, con- 

 necting with the base of the proboscis. 



Arms somewhat rounded, and bifurcating on the fifth or sixth piece above 

 the second radials; and in all but the anterior ray, one of the divisions (the 

 inner one) remains simple, and the other subdivides again on the sixth, seventh 

 or eighth piece, while the anterior arm bifurcates first on the sixth piece, and 

 each of its subdivisions again on the eighth or tenth piece above. First, and 



[July 



