312 PROCEEDINGS OF THE ACADEMY OF 



body (to say nothing of other differences), remove it, however, at 

 once from that genus, as well as from Mariacrinus, from which 

 latter it also differs materially in the structure of its arms and in 

 other important characters. I suspect that it may be found to 

 present sufficiently marked differences in this apparent fusing of 

 the rays, as it were, into the walls of the body, up to the first 

 bifurcation, to entitle it to rank as the t3q:)e of a new group ; but, 

 without better specimens for study and examination, I prefer to 

 refer it provisionally to Dendrocrinus, which can scarcely be re- 

 garded as more than subgenerically distinct from Poteriocrinites. 



In general appearance, it seems to resemble most nearly Dendro- 

 crinus acutidactylus and D. gregarius of Billings. It differs from 

 the first, however, in having a more slender body, with propor- 

 tionally longer arms, much less diverging at the bifurcations, 

 as well as in having the two branches at each division unequal. 

 From the latter species it also differs in the nature of its arms, 

 as well as in having its column composed of very short pieces not 

 presenting a bead-like appearance. 



Locality and position. — Cincinnati group of the Lower Silurian, 

 in the lowest beds seen at Cincinnati, Ohio. The survey is under 

 obligations to Mr. C. B. D^^er, of Cincinnati, for the use of the 

 only known specimens of this species. 



POTERIOCEINITES (DENDROCRINUS) CINCINNATIENSIS, Meek. 



Body of about median size, obconic, or tapering to the column 

 from above, nearly or quite as wide at the top of the first radials 

 as the height to the same. Base forming a rather rapidly ex- 

 panding cup, nearly twice as wide as high. Basal pieces of mo- 

 derate size, wider than high, pentagonal in form, and each provided 

 with a minute notch at the middle of the under side, correspond- 

 ing to a furrow extending up each side of the column. Subradial 

 pieces about twice as large as the basals, as wide as long or slightly 

 wider, all hexagonal excepting the one on the anal side, which is 

 heptagonal and a little larger than the others. First radial piece 

 in the ray on the right of the anal series a little smaller than the 

 subradials, and pentagonal in form, supporting on its upper 

 truncated edge a rather shorter piece, corresponding to the 

 slightly larger first radials in the other rays, and, like the latter, 

 rounded on the outer side, with a pentagonal outline, and a some- 

 what narrowed facet above for the reception of the first free 



[February 13, 



