TROOST 's CRINOIDS OF TENNESSEE E. WOOD. 



77 



The following description of Crumensecrinites ovalis is by Troost : 



Body elongated ellipital terminating at its base in a solid point, showing no trace 

 or cicatrice for the insertion of a column [?]. 



Pelvis [base] — divisible into three irregular pentagons; when joined together they 

 form three re-entering angles and three straight edges the first, (re-entering angles) 

 supporting three heptagonal costals [two radials and an anal] while the straight edges 

 support three hexagonal costals [radials]. 



The places between the interscapulars [interbrachials] and arms are covered with 

 an arrangement of small plates in the form of a rosette. All the plates, with the 

 exception of those of the pelvis, [base] are ornamented with slight elevated ridges 

 radiating from the center of the plates and disappearing before they reach the margin. 



This fossil is mostly imbedded in limestone (an aggregate of water worn small frag- 

 ments of fossils) showing the whole of the pelvis and more than half of the body and 

 hands. 



I discovered it in Decatur County, Tennessee. It is the only one that I have seen. 



Observations. — The genus Crumensecrinites was founded on a 

 specimen which was believed to be without a column, but it is un- 

 doubtedly a Periechocrinus from which a part of the base has been 

 broken away. It is apparently identical with P. tennesseensis. 



The specimen shows ridges traversing the radial series, as is usual 

 for the species, and two of the radials have traces of transverse 

 ridges, but I am unable to distinguish ridges radiating from the cen- 

 ters of all the plates, as described by Troost. 



Formation and locality. — Brownsport limestone. Perry and De- 

 catur counties, Tennessee. 



Cat. Nos. 39915, 39916, U.S.N.M. 



PERIECHOCRINUS DUBIUS (Troost), new name. 



Actinocrinites tennesseex (in part) Troost, MSS., 1850. 

 Gilbertsocrinites (?) dubius, Troost, MSS., 1850. 



Saccocrinus speciosus Roemer, Die Sil. Fauna d. west. Tennessee, I860, p. 42, 

 pi. in, figs. 3a, b, c. — Shumard (in part), Trans. Acad. Sci. St. Louis, II, 

 No. 2, 1866, p. 395 (catalogue name). — Miller, North Amer. Geol. and Pal., 

 1889, p. 279 (catalogue name). 



Periechocrinus speciosus (in part) Wachsmuth and Springer, Rev. Palseocri- 

 noidea, II, 1881, p. 133 (catalogue name); North Amer. Crinoidea Camerata, 

 1 1897, p. 521. 



The following description of Gilbertsocrinites (?) dubius is by Troost: 



It has a funnel shaped form; it is more or less angular and somewhat bent at its base. 

 My most perfect specimen is siliceous and no joints of plates are perceptible. From 

 a mutilated specimen it appears, that it is composed of a pentagonal pelvis [base], 

 having five reentering angles in which are placed five heptagonal first costals [radials] 

 which support five hexagonal second costals [first primibrachs] between which are 

 placed five pentagonal inter costals [interbrachials]. Then follow a number of polyg- 

 onal plates, the arrangement of which its mutilated state prevented me from 

 ascertaining. 



