TROOST 'S CRINOIDS OF TENNESSEE— E. WOOD. 



93 



tion resembles that of material from Huntsville, the latter reference 

 may be an error. 



Cat. No. 39969, U.S.N.M. 



HYDREIONOCRINUS SPINOSUS, new name. 



Hydreionocrinus depressus Wetherby, Journ. Cincinnati Soc. Nat. Hist., Ill, 

 1881, p. 325, pi. ix, figs. 1-4, 6.— Weller (in part), Bull. No. 153, IT. S. 

 Geol. Surv., 1898, p. 310 (catalogue name). 



The specimens representing this species were carefully described 

 by Wetherby (1881, p. 325) and referred to Zeacrinus depressus 

 (Troost) Hall on the authority of Mr. Wachsmuth, although the 

 author himself differed from Wachsmuth on the subject of the 

 specific identification. He says, " Though Mr. Wachsmuth, to 

 whom I have sent specimens of these crinoids, refers them to the 

 species described by Meek and Worthen under the name of Zea- 

 crinus armiger, Proc. Acad. Nat. Sci. Phila., and Z. depressus Troost, 

 as defined by Hall, a I have every reason to believe that this ref- 

 erence is incorrect and that the fossils here figured are undescribed 

 species. I do not, however, forget Mr. Wachsmuth' s claim to be 

 regarded as the highest American authority on these fossils, and 

 refrain from adding any new names to the forms herein described 

 at present, the more especially as I have had no authentic exam- 

 ples of the two species above mentioned with which to compare 

 the specimens now under consideration and must therefore rely 

 upon my own interpretation of the descriptions and figures in illus- 

 tration of the species mentioned." 



With the types of Hydreionocrinus depressus before me for com- 

 parison with Professor Wetherby' s careful description and figures, 

 it is evident that he was correct in believing that his specimens 

 constituted a species distinct from that of Troost. The basals of 

 Wetherby' s type are relatively much shorter than those of H. de- 

 pressus, having a length about equal to the width, and the long 

 radianal plate of the latter is represented in the former by a short 

 hexagonal plate, no part of which occupies a position between a 

 basal and radial. 



The first of the species mentioned above, H. armiger, has already 

 been separated by Wachsmuth and Springer (1886, p. 245) as H. 

 wetherbyi, and for the second the name H. spinosus is now proposed. 



Formation and locality. — Chester group. Pulaski County, Ken- 

 tucky. 



« Geol. Rep. Iowa, I, Pt. 2, p. 546. 



