TKOOST'S CRINOIDS OF TENNESSEE E. WOOD. 



31 



The description of Cupellsecrinites Isevis by Troost is as follows: 



Pelvis [base] almost flat, more or less depressed towards the center; a circular ali- 

 mentary perforation [lumen], surrounded with an elevated border. No division per- 

 ceptible not even in the young specimens. 



Costals [radials] five, hexagonal, longitudinally depressed, resting with one of the 

 broad sides upon the large pelvis and forming with the pelvis the flat bottom of the cup. 



Scapulars [secundibrachs] five [ten] quadrilateral — having an excavation of a semi- 

 circular form in the center of the superior margin [of the two plates] for the reception 

 of the arms — This superior margin forms part of the border of the cup. Inter-scapulars 

 [interbrachials] five, pentagonal, an angle of which fills the re-entering angle formed 

 by the junction of two hexagonal costals [radials] — the superior margin completing 

 the border of the cup. 



Arms — five, dividing into two hands (such is the case with all the other species — in 

 this that part is mutilated). 



Column cylindrical with circular alimentary canal [lumen]. 



Capital integument unknown. 



It is remarkably flat, its diameter being 40 mill. m. while its height is only 13 mill. m. 

 The surface is smooth. 



The description of Cupellsecrinites buchii by Troost is as follows: 



It differs from C. laevis in the construction of the scapulars [secundibrachs] which at 

 the superior margin receive several small plates projecting much above the general 

 level in the centre of the body; on both sides of this projection is a horse shoe excava- 

 tion for two hands? Consequently the division of the arms takes place immediately 

 at the body which is not the case with the C. laevis. It is also more elevated, the cos- 

 tals [radials] being in proportion longer and more raised towards the border of the cup, 

 and slightly concave towards the centre. 



Observations. — Troost described under the name of Cupellsecrinites 

 buchii a large Marsipocrinus which is apparently of the same species 

 as Marsipocrinus tennesseensis (Roemer). Nearly all of the outer 

 surface of the specimens has been removed and several of them are 

 quite smooth, while others show traces of fine radiating ridges. 



Cupellsecrinites buchiiTroost was separated from C. Isevis Troost on ac- 

 count of a supposed difference in the branching of the arms. In C. Isevis 

 the plates of the calyx are not preserved above the first secundibrachs, 

 and the large hemispherical opening thus produced was supposed to 

 be the opening for a single arm which branched later. C. buchii is said 

 to be a more elevated form but this appearance is also produced by the 

 greater number of plates preserved in its calyx. So far as preserved 

 the plates of C. Isevis correspond with those of C. buchii, and it is there- 

 fore referred with the latter to Marsipocrinus tennesseensis (Roemer). 



Formation and locality. — Brownsport limestone, Eucalyptocrinus 

 zone of the Beech River formation. Decatur County, Tennessee. 

 The following species are mentioned by Troost as occurring in asso- 

 ciation with Marsipocrinus tennesseensis: 



Calceola tennesseese, Terebratula [ Whitfieldella] oblata, Leptaena 

 [Spirifer] imbrex, Leptaena depressa [rhomboidalis], Pentremites 

 [Troostocrinus] reinwardtii, Calymene blumenbachi var. niagarensis. 



Cat. Nos. 39925, 39928, U.S.N .M. 



