TROOST 's CRICOIDS OF TENNESSEE E. WOOD. 



95 



EUPACHYCRINUS BOYDII Meek and Worthen. 



Plate 7, figs. 1, 2, 3, 4, 5. 



Cyathocrinites crateriformis Troost, Proc. Amer. Ass. Adv. Sci., II (read 1849), 

 1850, p. 61 (nomen nudum); MSS., 1850. 



Ewpachycrinus boydii Meek and Worthen, Proc. Acad. Nat. Sci. Phila., 1870, 

 p. 30; Geol. Surv. Illinois, V, 1873, p. 554, pi. xxi, fig. 6. — Wachsmuth and 

 Springer, Rev. Palseocrinoidea, I, 1879, p. 138 (catalogue name); III, 1886, 

 p. 249. — Miller, North Amer. Geol. and Pal., 1889, p. 245 (catalogue name). — 

 Weller, Bull. No. 153, U. S. Geol. Surv., 1898, p. 264 (catalogue name). 



Cyathocrinus crateriformis Wachsmuth and Springer, Rev. Palseocrinoidea, I, 

 1879, p. 148 (catalogue name). — Miller, North Amer. Geol. and Pal., 1889, 

 p. 235 (catalogue name). 



The description by Troost is as follows: 



Our crinoid resembles in external form some species of the genus Poteriocrinites par- 

 ticularly the P. granulosus of Phillips; but if we observe the arrangement of the plates, 

 it can not be classed in this genus. According to Phillips Poteriocrinites is composed of 

 a pelvis [infrabasals] (not known to Miller) and five costals [basals] (pelvis of Miller) 

 consequently Miller's becomes a second series of costals [radials]. The crateriformis 

 is composed of a pentagonal pelvis divisible into four [five] parts [infrabasals], five 

 costals [basals] five scapulars [radials] and three interscapulars [anal plates]. We see 

 that it does not belong to the category of the Poteriocrinites, nor does it exactly agree 

 with the characters of the Cyathocrinites, the crateriformis having two hexagonal and 

 one irregular interscapulars [anal plates]. We class, it provisionally with the Cyatho- 

 crinites, till more complete specimens authorize us to form for it a new genus. 



The Cyathocrinites crateriformis has a cylindrical column perforated with a circular 

 alimentary canal [lumen]. Pelvis [base] — pentagonal, very small, more or less con- 

 cave, forming the bottom of a deep cavity formed by the level part of the large tumid 

 pentagonal costals [basals]. Five very tumid pentagonal costals [basals], the lower 

 part of which form the whole of the sides of the pelvic cavity — then turning outwards 

 they form the base of the cup, and turning upwards they form the side of the cup, 

 where they assume a tumid almost globular form. Then follow five broad pentagonal 

 scapulars [radials] the superior surface of which is provided with a groove for the recep- 

 tion of arms. Three irregular pentagonal intercostals [anals] complete the rim of the 

 cup. The plates are all tumid. The whole of the complicated figure will be better 

 understood by consulting the plates. 



It was discovered in Decatur County, Tennessee. 



Observations. — -Troost's specimen of this species preserves only the 

 dorsal cup to the top of the radials. His figure represents the sides 

 of the calyx as much too divergent. They are vertical or even 

 inclined slightly inward toward the top. 



Formation and locality. — Chester group, Chester, Illinois; Ten- 

 nessee? The locality given for Doctor Troost's specimen is Decatur 

 County, Tennessee, but his collections from Decatur County are from 

 the Brownsport limestone and the genus Ewpachycrinus is not known 

 to occur lower than the Mississippi horizon, hence there is probably 

 an error in the locality label, 



Cat No. 39971, U.S.N. M, 



