140 PROCEEDINGS OF THE ACADEMY OF 



ing tip along each division of the arms to their extremities. The sntures be- 

 tween the primary radials seem to be a little gaping, as in Scapkiocrinus, to 

 which the species appears to bear some relations in other respects. The anal 

 side of the specimen being imperfect, we are left in some doubts in regard to 

 the generic characters of this species. In some respects it seems to agree 

 more nearly with Cyathocrinus than Poteriocrinus, though it evidently pos- 

 sessed more anal pieces than occur in the latter genus. The carinated char- 

 acter of its arms and primary radial pieces is a peculiarity that will readily 

 distinguish it from any other species with which we are acquainted. 



Locality and position. Burlington, Iowa. Burlington Limestone. Mr. 

 Charles Wachsmuth's collection. 



Subgsnus SCAPHIOCRINUS, Hall, 1858. 



Poteriocrinus (Scaphiocrinus ?) carbonarius. Body small, depressed or 

 basin-shaped below the summit of the subradial plates, rounded and concave 

 below, composed of thick, convex, smooth plates, which are connected by 

 distinctly impressed sutures. Base small, concave, and pentagonal in out- 

 line. Subradial plates a little longer than wide, directed obliquely outwards 

 from the base, and curving upwards at the extremities ; all pentagonal, ex- 

 cepting one on tbe anal side, which is a little truncated at the upper extremity 

 for the reception of one of the anal pieces ; upper angle of each rather salient. 

 First radials nearly twice as large as the subradial pieces, wider than long, 

 pentagonal, or subheptagonal, the upper side being truncated, and concave 

 on its outer slope. Second radial pieces nearly twice as long as wide, pent- 

 agonal in outline, rounded on the outer side, and distinctly constricted around 

 the middle ; supporting the first division of the arms on their superior sloping 

 sides. 



We are in some doubt in regard to the generic relations of this species, not 

 having seen the arrangement of its anal pieces. It agrees with Prof. Hall's 

 subgenus Scaphiocrinus in the elongated and constricted form of its second 

 radial pieces, as well as in having the sutures between these pieces and the 

 first radial plates widely gaping. It differs, however, from the typical forms 

 of that group in having a concave base. It also seems to differ from Scaphio- 

 crinus, as well as the typical forms of Poteriocrinus in apparently having be- 

 tween the second radials small interradial pieces, yet we are not sure the 

 pieces seen occupying the interradial spaces may not be fragments of the arms 

 that have accidentally been placed in this position. We suspect, however, it 

 may belong to an undescribed genus, but prefer to place it in the genus Poterio- 

 crinus, until we can see better specimens. 



Locality and position. Near Springfield, 111. Coal Measures. 



Poteriocrinus (Scaphiocrinus) solidus. Body small but strong, calyculate 

 or inversely bell-shaped below the top of the first radial plates ; sides expand- 

 ing rather gradually, with a slightly convex outline to near the middle of the 

 first radial plates, above which they curve a little outwards. Base depressed, 

 spreading from the summit of the column ; pentagonal in outline, each piece 

 showing a rather short pentagonal face above the column. Subradials about 

 as wide as long, three hexagonal and two heptagonal. First radial plates 

 nearly twice as large as the subradials, wider than long, and pentagonal 

 in form, the upper side being transversely truncated and a little concave ; se- 

 cond radial plate narrower than the first, longer than wide, pentagonal in 

 form, (excepting in the anterior ray, which is simple,) and distinctly con- 

 stricted around the middle. 



First anal (or subanal) plate pentagonal, and resting between the upper 

 sloping sides of two of the subradial plates ; connecting on the left with an- 

 other, which rests upon the superior truncated side of a subradial. The 

 upper truncated extremity, of the first anai or subanal plate supports a third 



[June, 



