1886.] NATURAL SCIENCES OF PHILADELPHIA. 211 



arrangement, however, was ascertained in places where portions 

 of this integument had been weathered. 



The oral pyramid, which occupies the centre of figure, is placed 

 on a level with the covering pieces to wliich it is closely attached. 

 It rests against the truncated margins of the interradials, which 

 for its reception are slightly excavated. It is composed of five 

 subequal pieces, which are so closely united by suture laterally 

 and centrally, that the suture lines are rarely visible, and the 

 plates appear as if forming a single piece. 



The anal aperture is located ventrally, near the top of one of 

 the interradial processes, at the place where two of the limbs meet 

 with the interradial. In its usual preservation it consists of a 

 rather large circular opening, which, however, in perfect speci- 

 mens is closed by a valve of from four to six small pieces. 



The Stephanocrinus which Hall described and figured in the 

 28th Rep. of the N. York St. Cab. Nat. Hist. (Second Edition), 

 p. 146, PI. 14, figs. 15-20, is in our opinion specifically distinct 

 from S. gemmiformis, and even generically unless the small inter- 

 radial plates are very incorrectly outlined. 



S. osgoodensis S. A. Miller ( Codaster osgoodensis) , Cincin. Journ. 

 Nat. Hist., vol. ii, PI. 10, figs. T and T a, which the author in his 

 Catalogue of the Palseoz. Fossils (Second Edition) referred to 

 Stephanocrinus is described from internal casts, and too incom- 

 pletely known for identification. St. pulchellus, S. A, Miller, is 

 a Codaster. 



The column is small, and composed of comparatively long 

 joints. 



Geological Position, etc. The genus has been found exclusively 

 in the Niagara group of America. 



The following species have been described : 



1842. Stephanocrinus angulatus Conrad. (Type of the genus). Journ. Acad. Nat. 

 Sci. Phila., vol. viii, p. 279, PI, 15, fig. 8. Pictet, 1867, Traite de Paleont., 

 vol. iv, PI. 99, fig. 23. F. Roemer, 1851, Wiegmann's Archiv., Jahrgang 

 xvi, pp. 365-375, PI. 5. Hall, 1851, Palaeont. N. York, vol. ii, pp. 213 and 

 351, PI. 48, fis. 1 a-m, and PI. 85, figs. 1-4. Niagara group. Lockport, N. 

 York. 



1851. St. gemmiformis Hall, Palajont. N. York, vol. ii, p. 215, PI. 48, figs. 2a-t; also 

 1879, 28th Rep. New York St. Cab. Nat. Hist., p. 146, PI. 14, figs. 15-20 ; also, 

 1881, 11th Ann. Geol. Rep. Indiana by CoUett, p. 279, PI. 13, figs. 15-20,^ 

 Rochester, N. Y., and Waldron, Indiana (?). 



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