152 



PROCEEDINGS OF THE A^.iDEMY OF 



basal pieces proportionally much larger and more tumid, and its radials above 

 the first narrower and proportionally longer. From C. protuberans it also 

 differs in not having its first radial pieces tumid, while one of its arms after 

 the first division is seen to bifurcate again on the third piece, instead of 

 merely giving off small lateral branches, as in C. protuberans. 



Our specimen being defective on the anal side, we have been unable to de- 

 termine whether it has one only, or two anal pieces soldered in the wall of 

 the cup, though it appears to have but one. 



Locality and position. Keokuk limestone, of subcarboniferous series. Near 

 White Hall, Green County, 111. 



CYATHOCRINUS ENORMIS, M. & W. 



Poteriocrinus ? enormis,M. & W. Proceed. Acad. Nat. Sci., June", 1861, p. 137. 

 Although this species possesses the structure and arrangement of the parts 

 composing the walls of the body, including the anal pieces, of Poteriocrinus. 

 the fact that it has a slender lateral proboscis, not larger than one of its armsj 

 instead of a large trunk nearly as wide as the body, as seen in typical species 

 of Poteriocrinus, leads us to the conclusion that it more properly belongs to 

 the allied group of Ci/athocrinus. This conclusion is also sustained by the 

 appearance of an opening in the summit, near the small lateral proboscis. 

 These differences in the structure of the summit will probably be found of 

 more importance as a distinction between these two groups, than the fact of 

 one or two more or less anal pieces being included as a portion of the walls 

 of the body. 



Genus POTERIOCRINUS, Miller, 1821. 



POTERIOCRINUS (ZEACRINUS) CARBONARIUS, M. & W. 



Poteriocrinus (Scarphiocrinus?) carbonarius, M. & W. Proceed. Acad. Nat. 

 Sci., June, 1861, p. 140. 

 This species has the elongated and constricted second radial pieces, as well 

 as the gaping sutures between these and the first radials, characterizing Scar- 

 phiocrinus, but differs from the typical forms of that group in having a con- 

 cave base. In the latter, as well as some of its other characters, it agrees 

 with Zeacrinus, to which it seems to more properly belong. 



Genus ACTINOCRINUS, Miller, 1821. 



ACTINOCRINUS PISTILLUS, M. & W. 



Body, exclusive of the proboscis, sub-pyriform ; the sides rising nearly ver- 

 tically from the base to the summit of the first radial pieces ; thence gradually 

 expanding to the secondary radials, after which they expand very rapidly, so 

 as to cause the brachial pieces to be directed horizontally outwards, or nearly 

 so, at about the middle of the body. Above the horizon of the arm bases, the 

 dome rises at first vertically, but very soon rounds inward, and rises with a 

 moderately convex slope to the base of the subcentral proboscis. Base trun- 

 cated and flat below, with a thick dilated margin notched at the suture, so as 

 to present a trilobate outline, as seen from beneath ; columnar facet a little 

 concave, and about one-third as wide as the base. Basal pieces twice as wide 

 as high, and hexagonal in form, the inferior margin being much longer than 

 any of the others. First radial pieces wider than long, smaller than the basal ; 

 three of them heptagonal, and two hexagonal. Second radial pieces very 

 small, twice as wide as high, and transversely oblong, or sometimes with one 

 of the superior lateral angles truncated by one of the interradials, so as to pre- 

 sent an irregular pentagonal form. 



Third radials a little larger than the second, pentagonal or hexagonal in 

 form, and supporting on each superior sloping side, a secondary radial piece, 



[Aug. 



