66 



BULLETIN 64, UNITED STATES NATIONAL MUSEUM. 



primaxils.. Higher plates of the calyx indeterminable. The num- 

 ber of the arms cannot be accurately determined, but there are at 

 least twenty and probably more, as indicated by the size of the arm 

 bases which are preserved and the portion of the periphery belonging 

 to each ray. 



There is apparently but one large interbrachial. First anal plate 

 larger than the radials, followed by three smaller plates, and these 

 by the two adjacent secundibrachs and three additional small plates. 



All plates of the dorsal cup bear at the center a large, rounded, 

 but not very prominent, node. Surface covered with fine granules. - 



Plates of the tegmen small in comparison with those of the dorsal 

 cup, each bearing a sharp spine at its center. Less than half of the 

 tegmen is preserved, hence the character of the proboscis is unknown. 



Observations. — Batocrinus sayi is distinguished from other described 

 species of the genus by the comparatively small base, the extremely 

 large radial plates, and the presence of but one interbrachial. The 

 species resembles B. gibbosus Troost in having but one interbrachial 

 and in the spinose tegmen plates, although the spines of its tegmen 

 are narrower and longer than those of B. gibbosus. It differs from 

 the latter species in the size and shape of the basals and radials 

 and in the form of the surface nodes which are rounded instead of 

 transverse. 



Formation and locality. — Keokuk horizon of the Tullahoma forma- 

 tion. White's Creek Springs, Davidson County, Tennessee. 

 Cat. No. 39899, U.S.N.M. 



Genus ERETMOCRINUS Lyon and Casseday. 



ERETMOCRINUS PRAEGRAVIS Miller. 



Actinocrinites cornutus Troost, Proc. Amer. Ass. Adv. Sci., II (read 1849), 1850, 

 p. 60 (nomen nudum). 



Actinocrinus cornutus Shumard, Trans. Acad. Sci. St. Louis, II, No. 2, 1866, 

 p. 343 (catalogue name). — Wachsmuth and Springer, Rev. Palseocri- 

 noidea, II, 1881, p. 224 (catalogue name). — Miller, North Amer. Geol. and 

 Pal., 1889, p. 217 (catalogue name). 



Eretmocrinus praegravis Miller, Adv. Sheets, 18th Rep. Ind. Dep. Geol. and 

 Nat. Hist., 1892, p. 37, pi. vi, figs. 5, 6. — Wachsmuth and Springer, North 

 Amer. Crinoidea Camerata, 1897, p. 405, pi. xxxiv, figs. 9, 10. — Weller, 

 Bull. No. 153, U. S. Geol. Surv., 1898, p. 251 (catalogue name). 



The description by Troost is as follows : 



The crinoid now under consideration was at first taken for the Melocrinites gibbosus 

 figured by Goldfuss, plate 64, which resembles more or less our fossil, it being very 

 difficult to form a just idea of the form and arrangement of the plates. Yet notwith- 

 standing this apparent irregularity it is easily seen that the pelvis [base] is composed 

 of three parts, that it support's two series of six plates of costals [radials and anal plate], 

 which support again five scapulars [primibrachs] with a cuneiform summit upon 



