96 PROCEEDINGS OF THE ACADEMY OP [1886. 



upwards and inwards, forming partitions between the arm bases, 

 leaving but a small space for the reception of the arms. 



Column round, with a stellate central canal, its angles directed 

 radially. 



Geological Position, etc. Stortingocrinus is restricted, so far 

 as known, to the lower beds of the Devonian of Europe. 



*1838. Stortingocrinus decagonus (Goldfuss) Platycrinus decagonus, Nova Acta 

 Ac. Leopold, xix, i, p. 345. Schultze, Platycrinus (Stortingocrinus) deca- 

 gonus; Monogr. Echin. Eifl. Kalk., p. 70, PI. 10. Devonian. Eifel, 

 Germany. 



*1S55. St. fritillus, (Wirthgen and Zeiler), Type of the genus. Platycrinus fritillus, 

 Verb, naturh. Verein f. Rheinl., Jahrg. xii (n. sen), p. 80, PI. 10, figs, i and 

 5. Schultze, Platycrinus (Stortingocrinus) fritillus, Mon. Echin. Eifl. 

 Kalk., p. 69, PI. 10, figs. 8-8 f. Devonian. Eifel, Germany. 

 Syn. Platycrinus asper, P. pusillus, P. rugosus, P. scobiculatus and P. 

 scaber Goldfuss, and P. minutus Schurr. 



*1866. St. trifidus (Schultze), Platycr. (Stortingocr.) trifidus, Monogr. Echin. Eifl. 

 Kalk., p. 70, PI. 10, figs. 8a-g. Devonian. Eifel, Germany. 



PISOCRINTJS De Koninck. 



1858, De Koninck. Bull, de 1' Acad. Roy. de Belgique (Ser. 2), iv, p. 104. 



1873. Salter, Cat, Cambr. Museum, p. 128. 



1879. Handb. d. Palseontologie i, p. 348. 



18T8, Angelin, Iconogr. Crin. Suec, p. 20, 



1879. S. A. Miller, Joum. Cincin. Soc. Nat, Hist. (July). 



Syn, Symbathocrinus (in part), F, Roemer, Silur. Fauna, "West 



Tenn., p. 55, 

 Syn. (?) Triacrimts, Miinster, 1839 (in part), Beitrage zur Petre- 



factenkunde, p, 4. 

 Syn, Symhathocrinus (in part), Roemer, 1860, Silur,, Fauna West. 

 Tennessee, p, 55. 



Pisocrinus is closely allied to Triacrinus, but the latter is said 

 to have three basals; Pisocrm us has five. The arrangement of 

 the other calyx plates is identical, and also the arm structure. 

 Schultze, who observed in the Eifel species only three basals, 

 postulated from this that the Silurian species from Sweden, for 

 which De Koninck had established the genus Pisocrinus, also 

 consisted of but three plates, Angelin, who succeeded Schultze, 

 and who had at his command the extensive collections of the 

 Stockholm Museum, describes the genus with five basals, and all 

 his figures show five plates. We also examined from the same 

 horizon in America several hundred specimens of at least three 

 species from Western Tennessee, all of which have five basals and 



