TROOST *S CRINOIDS OF TENNESSEE E. WOOD. 



51 



not show a marked constriction of the body wall. This is appar- 

 ently not a constant feature for the species, as indicated by Miller 

 and Gurley's fig. 6, plate 5, in which such constriction does not 

 appear. 



Doctor Troost's description of these specimens is as follows: 



The form of this species resembles that of E. phillipsi but the plates are tumid [?] 

 and the cavity for the insertion of the column is circular [?] and not deep. 



Although the plates have undergone considerable solution, which 

 has removed much of the surface, they appear, contrary to Troost's 

 observation, to be flat plates without ornamentation. The basal 

 excavation also appears pentagonal rather than circular. 



Formation and locality. — Brownsport limestone. Decatur County, 

 Tennessee. 



Cat. Nos. 39957, 39958, U.S.N.M. 



EUCALYPTOCRINUS PHILLIPSI Troost. 



Plate 10, figs. 9, 10; Plate 13, figs, 2, 3, 4. 



Eucalyptocrinites phillipsi Troost, Proc. Amer. Ass. Adv. Sci., II (read 1849), 



1850, p. 60 (nomen nudum); MSS., 1850. 

 Eucalyptocrinites Isevis Troost, Proc. Amer. Ass. Adv. Sci., II (read 1849), 1850, 



p. 60 (nomen nudum); MSS. 1850. 

 Eucalyptocrinus phillipsi Shumard, Trans. Acad. Sci. St. Louis, II, No. 2, 1866, 



p. 370 (catalogue name). — Wachsmuth and Springer, Rev. Palseocri- 



noidea, III, 1885, p. 128 (catalogue name). 

 Eucalyptocrinus Isevis Shumard, Trans. Acad. Sci. St. Louis, II, No. 2, 1866, 



p. 370 (catalogue name). — Wachsmuth and Springer, Rev. Palseocri- 



noidea, III, 1885, p. 128 (catalogue name). 



The following description is by Troost: 



It is inverted conical. The cavity for the insertion of the column formed by the 

 pelvic [basal] plates and part of the first costals [radials] is pentagonal, being very 

 large and deeper than in any other species, it being 12 mil. met. deep while the height 

 of the cup is 22 mil. met. 



The specimens referred to Eucalyptocrinites Isevis, apparently differ 

 from E. phillipsi only in the narrower orifice of the basal excava- 

 tion, but as this is a variable feature it seems insufficient ground for 

 separating them as distinct species. 



The following is Troost's description of E. Isevis: 



It is basin shaped and its surface smooth. The cavity for the column is pentago- 

 nal. In juvenile specimens the surface is crenate. 



This species is subject to various modifications in height whilst preserving the same 

 diameter. This being the only difference it can not be considered a sufficient reason 

 for forming different species." 



«Fig. 50 [2, 3, 4, plate 13] I consider as a variety of E. Isevis — Externally it re- 

 sembles the E. Isevis except that it is somewhat more inverted conical, but the visceral 

 cavity is in proportion much smaller, the superior rim very broad and the inside pen- 

 tagonal, whereas in the large specimen the sides are thin and circular. — From the 

 same locality. 



