146 PROCEEDINGS OP THE ACADEMY OP 



expansion, however, seems to be mainly due to the greater thickness of the 

 plates here, than to a corresponding increase in the size of the cavity within. 

 Plates of the proboscis of moderate size, and all indented at their corners. 



Height of body to the top of first radial pieces, 0-18 inch ; breadth about 

 0-32 inch ; length af arms beyond the top of the third radials, 1-68 inches; 

 length of proboscis above the first radials, 95 inch. 



This species is so distinct from all others known to us, that it is scarcely neces- 

 sary to compare it with any of them. It seems to be most like S. Ilal/i, Hall, 

 but differs in having its subradials so tumid as to give the body a truncated 

 appearance below, instead of an inversely campanulate outline. Its pinnulae 

 are also much stouter and less oblique, while its arms are entirely without the 

 little flattened spine-like projections along their backs seen in that species. 

 The stout pinnulae as seen extending between the arms present, with the latter, 

 a peculiar scalariform appearance, that suggests the specific name. 



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

 ton, Iowa. Lower Carboniferous. No. 282 of Mr. Wachsmuth's collection. 



ScAPHiocRiNus FiscELLus, M. and W. 



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

 high, rather broad and subtruncated below, with moderately expanded sides. 

 Base very small, flat, and hidden by the column, when the latter is attached. 

 Subradial pieces convex, curving under to connect with the base and extend- 

 ing about half waj' up the sides ; three of them presenting a pentagonal out- 

 line, and two hexagonal, (that is without counting a very obtuse angle doubt- 

 less existing at the middle of the under side of each, but hidden by the column). 

 First radials about the size of the subradial pieces, and pentagonal in form, 

 the upper side always truncated the full breadth. Second radials quadran- 

 gular, constricted in the middle, and expanded at the ends ; separated from 

 each other by spaces nearly half their own breadth, measuring at the middle. 

 Third radial pieces a little longer and narrower than the second, abruptly di- 

 lated at the ends, and strongly contracted in the middle ; each, with apparent- 

 ly the exception of one in the anterior ray (which seems to bear only one 

 arm), supporting two arms on their superior strongly sloping sides. 



Anal plates forming a double alternately arranged series, exactly as in the 

 last. Arms apparently simple from their origin on the third radials ; composed 

 of pieces as long as wide, or a little longer, and angular on the dorsal side ; each 

 piece always contracted in the middle, and expanded at the ends, particularly 

 at one of the upper lateral corners alternately on each side of the arm, for the 

 reception of the pinnulce, thus giving the arms a zigzag appearance. Pinnulaj 

 rather stout, and composed of pieces about as long as wide. 



Surface of the body with deep indentations at the corners of all the plates, 

 so as to form a comparatively strong ridge radiating to each side of the subradial 

 pieces, to connect with a similar one on each of the adjacent pieces. 



Height of body about 0-11 inch to the top of the first radial pieces, where 

 it measures about 0-17 inch in breadth ; length of arms, about 0'95 inch. 



This species is nearly related to the last, but in addition to being much 

 smaller, it differs in the strong radiating costaj of its body plates, as well as 

 in having its subradial plates merely convex, instead of tumid. Its arm joints 

 also differ in being proportionally longer, and contracted in the middle. 



Locality and poailion. — Lower division of the Burlington group; Burlington, 

 Iowa. Lower Carboniferous. No. 283 of Mr. Wachsmuth's collection. 



SCAPHIOCRINUS JUVENIS, M. and W. 



Body small, expanding rather rapidly from the column, or presenting a. 

 short, obconic form, with rather distinct sinuses between the radial scries ; 

 nearly twice as wide at the top of the first radials, as the height to the same 

 point. Base small and short, or several times wider than high, but projecting 



[July, 



