68 BULLETIN 64, UNITED STATES NATIONAL MUSEUM. 



latter authors separate the two species by the number of arms, 

 describing fourteen arms for Batocrinus spinosus and twelve for Eret- 

 mocrinus praegravis. In the original description of E. praegravis some 

 uncertainty is expressed as to the number of arms. Small apertures 

 in addition to the twelve undoubted arm openings are mentioned as 

 being possibly related to the arms. Wachsmuth and Springer describe 

 definitely fourteen arms for E. praegravis, the same number possessed 

 by Batocrinus spinosus. The dorsal cup of the latter is, however, 

 lower, the anal tube larger, and the specimens also much smaller than 

 Eretmocrinus praegravis, and it is therefore regarded as a distinct 

 species. 



Miller and Gurley assign their species to Batocrinus and suggest 

 that the genus Eretmocrinus be abandoned, assuming that the genus 

 is founded upon the size and curvature of the proboscis. As noted 

 by Wachsmuth and Springer, Eretmocrinus differs from Batocrinus in 

 the paddle-shaped arms, the projecting basals, the eccentric anal tube, 

 and other well-marked features which entitle it to rank as an estab- 

 lished genus. Since Batocrinus spinosus Miller corresponds with Eret- 

 mocrinus in all the features available for comparison and is closely 

 related to Eretmocrinus praegravis, it should be referred to Eretmocrinus 

 as is here done. 



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

 tion. Cannon County, Tennessee; Little Barren River, Kentucky. 



Cat. No. 39895, U.S.N.M. 



ERETMOCRINUS RAMULOSUS (Hall). 



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

 p. 60 (nomen nudum). — Shumard, Trans. Acad. Sci. St. Louis, II, No. 2, 

 1866, p. 342 (catalogue name). — Wachsmuth and Springer, Rev. PaUeo- 

 crinoidea, II, 1881, p. 223 (catalogue name). — Miller, North Amer. Geol. 

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



Actinocrinus ramulosus Hall, Rep. Geol. Surv. Iowa, I, Pt. 2, 1858, p. 615, pi. xv, 

 fig. 7. 



Eretmocrinus ramulosus Wachsmuth and Springer, Rev. Palseocrinoidea, II, 

 1881, p. 173 (catalogue name). — Miller, North Amer. Geol. and Pal., 1889, 

 p. 243 (catalogue name). — Wachsmuth and Springer, North Amer. Crinoidea 

 Camerata, 1897, p. 387, pi. xxxvn, figs. 4a, o, 5a, 6, c, d. — Weller, Bull. 

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



The following description is by Troost: 



This species is distinguished from A. urna [Batocrinus grandis] in the curve of the 

 cup which in the A. agassizi [Eretmocrinus ramulosus] is more uniformly rising and 

 not expanded at the rim, the plates are tumous but less elevated than in the A. urna 

 and are ornamented with irregular elevated ridges. The coronal integument is not 

 so lofty. 



Observations. — The specimens representing this species are much 

 distorted and enlarged by silicincation, but they show the essential 

 characters of the species. The base of the small anal tube and the 

 longitudinal nodes of the higher brachials are clearly shown. 



