148 PROCEEDINGS OF THE ACADEMY OF 



Arms very long, slender and rounded; one of them seen to bifurcate first on 

 the sixth, two others on the eighth, and another on the tenth piece, above the 

 second radials. Beyond these bifurcations it is evident from the number of 

 slender branches seen, that there must be other subdivisions, but the specimen 

 is not in a condition to show the details of the bifurcations. Arm pieces gen- 

 erally longer on the longer side than wide, but not arranged in zigzag; the 

 first two of each arm twice as long as wide, and somewhat contracted around 

 tlie middle. Proboscidiform extension very long, or nearly or quite equaling 

 the length of the arms, and somewhat narrowed at the extremity. 



Surface of the first radial plates strengthened by prominent, rounded, ra- 

 diating costie, two of which diverge downward from the mesial prominence 

 under the sinus for the second radials, to connect with others on the subra- 

 dials, so as to inclose profound triangular pits at the upper corners of the 

 latter ; while two similar ridges run laterally on each side of the sinus, 

 paraller to the upper margin, to connect with those similarly situated on each 

 adjacent first radial. On each subradial, the ridge extending down the middle 

 widens and becomes nearly obsolete at the base, where it connects with seve- 

 ral slender lines that continue on down converging toward the lower part of 

 each basal piece ; there being no pits or impressions at the meeting of the 

 corners of the basal and subradial pieces. 



Height of body to the top of the first radial, 0-96 inch ; breadth across at 

 the most protuberant part of the first radials, about one inch. Length of 

 arms from their origin on the second radials, about four inches. Length of 

 proboscidiform ventral extension, 3 85 inches. 



This fine species departs very widely from the typical forms of Scaphiocri- 

 nus in its large size, obconic body, strongly costate body plates, long bifurca- 

 ting arms, and particularly in having its second radial pieces so narrow in pro- 

 portion to the first, as to be separated from each other by interradial spaces, 

 wider than the second radial pieces themselves. Its anal series, although in- 

 cluding more pieces than we see in the typical Scaphiocrinus (being like that 

 of Poteriocrinites proper), does not differ from that of a large proportion of the 

 species usually included in Scaphiocrinus, with which the species agrees in hav- 

 ing onlj' two radial pieces to each ray. 



Specifically it is related to such forms as Cyathocrinun macropleurus, Hall, 

 and Poteriocrinus obuncus, White ; but it differs too widely from these and all 

 the other similar forms known to us, to render a comparison necessary. Cyatho- 

 crinus macropleurus was described from a specimen not showing either the anal 

 pieces or second radials, or the arms; Mr. Wachsmuth has specimens, however, 

 showing that it has several anal pieces, and two radials to each ray. He also has 

 specimens of the P. obuncus (which was also described from a specimen not 

 showing the arms and second radials), indicating that it agrees in these char- 

 acters with Scaphiocrinus It is possible such species should form a separate 

 section, or subordinate group. 



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

 Iowa. Lower Carboniferous. No. 303 of Mr. Wachsrauth's collection. 



Scaphiocrinus Coreyi, M. and W. 



Body of medium size, basin-shaped, or about twice as wide as high, rounded 

 and distinctly concave below. Base small, and nearly or quite hidden by the 

 column in the concavity of the under side. Subradial pieces comparatively 

 rather large, curving under to connect with the base, all presenting a general 

 hexagonal outline, excepting two on the anal side, which are heptagonal ; they 

 must each, however, have another obscure angle below. First radial pieces 

 about equaling in size the subradials, but proportionally wider, being some- 

 times slightly more than twice as wide as long, all pentagonal in form, the 

 upper side being much the longest, and the lateral margins short. Secoud 

 radials a little longer than the first, but narrower above, and more or less con- 



[July 



