TROOST *S CKINOIDS OF TENNESSEE — E. WOOD. 



71 



The figures are more likely to be correct as the first anal usually 

 corresponds more or less in size and shape with the radials. 



Alloprosallocrinus tuberculosus resembles in many respects A. 

 celsus Miller and Gurley, but important differences appear in the 

 descriptions of the two species, and in the absence of Doctor Troost's 

 type it can not be referred to A. celsus. The first primibrachs are 

 well-developed plates in A. celsus, minute in A. tuberculosus, the 

 interbrachials are two short plates in line instead of one long one, 

 and the second anal plate in A. celsus is short and followed by two 

 short plates. The tubercles on the dorsal cup of the latter are 

 extremely prominent while they are not described for A. tuberculosus, 

 but the name indicates that tubercles of some kind are present. 



ALLOPROSALLOCRINUS CONICUS Casseday and Lyon. 



Conocrinites lex Troost, Proc. Amer. Ass. Adv. Sci., II (read 1849), 1850, p. 60 

 (nomen nudum); MSS., 1850. — Wachsmuth and Springer, Rev. Palseo- 

 crinoidea, II, 1881, p. 229 (catalogue name). 



Alloprosallocrinus conicus Casseday and Lyon, Proc. Amer. Acad. Arts and Sci., 

 V, 1860, p. 29.— Wachsmuth and Springer, Rev. Palseocrinoidea, II, 1881, 

 p. 114 (catalogue name). — Miller, North Amer. Geol. and Pal., 1889, p. 222 

 (catalogue name). — Wachsmuth and Springer, North Amer. Crinoidea 

 Camerata, 1897, p. 407, pi. xlii, figs. 14 a, b, c. — Weller, Bull. No. 153, 

 TJ. S. Geol. Surv., 1898, p. 75 (catalogue name). 



Actinocrinus (Alloprosallocrinus) conicus Shumard, Trans. Acad. Sci. St. Louis, 

 II, No. 2, 1866, p. 353 (catalogue name). 



Alloprosallocrinus gurleyi Miller, 17th Rep. Geol. Surv. Indiana (Adv. sheets 

 1891, p. 58, pi. x, figs. 1, 2), 1892, p. 668, pi. x, figs. 1, 2. 



The description by Troost is as follows: 



It is distinguished from C. tuberculosus by being more circular, and by its coronal 

 integument being composed of polygonal plates which are slightly convex and almost 

 smooth, and by its proboscis not being so stout. These differences are not produced 

 by age— I have juvenile specimens of both species. 



It occurs at White's Creek Springs. 



Observations. — Two specimens in the Troost collection correspond 

 closely with the figures and description of Alloprosallocrinus conicus 

 Casseday and Lyon. In two of the rays, small first primibrachs are 

 differentiated, but this does not hold true of the other rays. 



Formation and locality. — Keokuk horizon of the Tullahoma forma- 

 tion. White's Creek Springs, Davidson County, Tennessee; Pilot 

 Knob, near Louisville, Kentucky; New Ross, Montgomery County, 

 Indiana. 



Cat. No. 39923, U.S.N.M. 



