298 PROCEEDINGS OF THE ACADEMY OF [1881. 



Interradial series constructed of numerous plates, the first 

 resting upon the posterior lateral sides of the first radials, and 

 between the second radials. There are two interradials in the 

 second series, three in the third, and others above. The posterior 

 side differs in having three plates in the second, and four to five 

 in the succeeding series. Construction of vault, and form and 

 position of the anus, unknown. 



Column long, round, slender, composed of short joints; central 

 perforation round and unusually large. 



Geological Position, etc. — The only known species occurs in the 

 Upper Silurian of Bohemia. 



1833. Scyphocrinus elegans Zenker. Beitr. Naturgoscb. Urw., p. 26, PI. 4, figs. 

 A-F; Munster, 1839, Beitr. zur Petrefactenk., p. 112, PI. 9, fig. 8; Quen- 

 stedt, 1850, Handli. d. Petref. p. 621, PI. f5, figs. 1-3; F. Roemer, 1S55, 

 Lethaea Geogn. (Ausg. 3). p. 255, PI. 4, figs. 6 a. b: Zitfel, 1879, Ilandb. >\. 

 Palaeon*'. i, p. 372. Upper Silur. Karlstein, Bohemia. 



11. DOLATOCRINUS Lyon. 



1857. Lyon. Geol. Rep. Kentucky, iii, p. 482. 



Syn. Cacahocrinus Troost. List of Grin. Tenn., 1850. 

 Syn. Cacahocrinus HaU. 15th. Rep. N. York, St. Cab. Nat. Hist., 

 p. 137. 



The name Cacahocrinus was proposed by Troost in his cata- 

 logue, but the genus was not defined until 1862 by HalL Lyon's 

 Dolatocrinus, which is identical with Cacahocrinus, was described 

 in 1857 and hence has priority. Lj^on described the genus with 

 three basals, Hall with five, but we doubt if either of them ever 

 found the sutures. The basal pieces are so closely anchylosed, 

 that we give them simply as constituting a solidly anchylosed 

 disk. Dolatocrinus differs from most allied genera in the anal 

 area, which in its construction is not distinct from the regular 

 interradial fields, but in this respect it resembles Stereocrinus, 

 which we place subgenerically under it. 



Generic Diagonis — Body spheroidal, depressed at both poles ; 

 wider than high. Calyx forming a low spreading basin, of which 

 the basals, the first, and partly the second radials form the bottom 

 part ; symmetry regularly pentahedral, the anal area not distinct 

 from the other interradial series. 



Vault hemispherical, depressed in the interradial portions, the 

 radial zones elevated, giving to the summit, viewed from that side, 

 a pentalobate aspect. 



