G2 The Ohio Journal of Science [Vol. XIX, No. 1, 



Historical Review. 



(Arranged in the order of description). 



Agelacrinites cincinnatiensis Roemer. Described in 1851 

 in the Verh. Naturh. Ver. fur Rheinl, und Westphal. Vol. VIII, 

 p. 372, Figs 3a, b. 



I quote Hall's description of the fossil, 1866-72. "It has 

 been a moderately convex disc usually with a diameter of % to % 

 of an inch, though it sometimes reaches a diameter of nearly 

 one inch which is about the size of the one figured by Dr. 

 Roemer. The disc is composed of numerous imbricating scale- 

 like plates; the rays all curving, four sinistral and one dextral 

 the intermediate areas composed of large plates. The mouth, 

 anal or ovarian aperture situated subcentrally in the largest 

 area and surrounded by a pyramid of small triangular plates. 



Agelacrinus Dicksoni Billings 1858, described in the Canadian 

 Organic Remains, Decade 3, p. 84, pi. 8. All the arms of this 

 species are counter clockwise, the anal pyramid is described as 

 an orifice surrounded by small plates. The type came from the 

 Trenton limestone, Chaudiere Falls, Ottawa, Canada. Bather 

 makes this the type of a new genus, Lebetodisciis . Geol. Mag. 

 V, vol. 5, pp. 543-550, pi. 25. 



Agelacrinus Billingsi Chapman 1860: No description of 

 this fossil is attainable other than that derived from Clarke, 

 New Agelacrinites, in which A. Billingsi from the Trenton 

 is said to be straight armed. 



Agelacrinus pileus Hall, 1866-72: "Body subglobose or 

 globular bellshaped, attached by the smaller extremity which is 

 composed of small squamiform plates. Rays from the top of 

 the dome and curving gently down the sides; four sinistral 

 and one dextral; the dextral and one sinistral surround the 

 posterior inter-radial space. The rays are formed by two 

 ranges of lanceolate plates, their ends pointed and interlocking 

 over the arm grooves, their bases originating in a transverse 

 pyramid formed by the union of two bifurcating or V-shaped 

 plates, one on each side of the base of the anterior ray, and a 

 single shield-shaped plate which is situated at the upper 

 extremity of the posterior inter-radial area. The extremities of 

 the rays appear to have been subsessile. The lateral arms are 

 in pairs, the anterior arm being separated from them by the 

 V-shaped plates. Inter-radial areas distinct, the posterior 



