28 BULLETIN" 64, UNITED STATES NATIONAL MUSEUM. 



Miller and Gurley [1894], and one of the specimens is flattened 

 laterally, thus increasing the resemblance to that species, but the 

 flattening of the Troost specimen is evidently accidental, as the plates 

 are more or less broken, while the type of S. angularis is oval in 

 transverse section. 



The species differs from S. granuliferous Wetherby [1880] in the 

 form of the radials. 



Formation and locality.—- Brownsport limestone. Decatur County, 

 Tennessee. 



Cat. No. 39938, U.S.N.M. 



SYMBATHOCRINUS ROBUSTUS Shumard. 



Plate 4, fig. 11. 



Donaticrinites simplex Troost, Proc. Amer. Ass. Adv. Sci., II (read 1849), 1850, 



p. 62 (nomen nudum); MSS., 1850. 

 Synbathocrinus robustus Shumard, Trans. Acad. Sci. St. Louis, II, No. 2, 1866, 



p. 397. — Meek and Worthen, Geol. Rep. Illinois, VI, 1885, p. 514, pi. xxix, 



fig. 4. _ 

 Symbaihocrinus robustus Wachsmuth and Springer, Rev. Palaeocrinoidea, III, 



1885, p. 169.— Miller, North Amer. Geol. and Pal., 1889, p. 285 (catalogue 



name).— Weller, Bull. No. 153, U. S. Geol. Surv., 1898, p. 618 (catalogue 



name). 



The original description by Troost is as follows: 



This certainly is the most uncomplicated crinoid that has been discovered. As the 

 specimen is mutilated I can not give a complete description of it. 



Its pelvis [base] is almost entirely wanting, only part of a plate exists which shows 

 that the superior margin of it is slightly elevated in the middle upon which succeed 

 five trapezoidal plates having their superior edge large and must be considered as 

 costals [radials] — immediately upon them follows a row of similar plates, having then 

 inferior margin large, which are the scapulars [primibrachs] and support five undivided 

 arms composed of broad plates. The plates are all thick consequently the visceral 

 cavity very small. 



Observations. — The specimen described by Troost as a new genus 

 and species with the name of Donacicrinites simplex appears to be 

 identical with Symbaihocrinus robustus Shumard. All the sutures 

 are represented in the figure as more depressed than appears on the 

 specimen, and the artist has figured two more plates on each arm 

 than are actually preserved, but the figure is otherwise a fair repre- 

 sentation of the specimen. 



Formation and locality. — Keokuk horizon of Tullahoma formation. 

 The specimen is recorded in the manuscript as from Decatur County, 

 but it is preserved in the same way as material from White's Creek 

 Springs, and is probably of the horizon represented at that locality. 

 The locality label of this specimen may have been confused with that of 

 Symbathocrinus troosti (S. tennesseex in part) which was labelled as 

 from White's Creek Springs, while it probably came from Decatur 

 County. 



