TROOST *S CRINOIDS OF TENNESSEE — E. WOOD. 69 



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

 tion. White's Creek Springs, Tennessee; Keokuk and Augusta, 

 Iowa; Nauvoo, Illinois. 



Cat. No. 39893, U.S.N.M. 



Genus ALLOPROSALLOCRINUS Casseday and Lyon. 



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

 (nomen nudum); MSS., 1850. 



Alloprosallocrinus Casseday and Lyon, Proc. Amer. Acad. Arts and Sci., 1860, 

 p. 29.— Shumard, Trans. Acad. Sci. St. Louis, II, No. 2, 1866, p. 353.— Meek 

 and Worthen, Geol. Rep. Illinois, V, 1873, p. 368 (not Meek and Worthen, 

 Proc. Acad. Nat. Sci. Phila., 1865, p. 164).— Zittel, Handb. d. Pal., I, 1879, 

 p. 370. — Wachsmuth and Springer, Rev. Pala30crinoidea, II, 1881, p. 113. — 

 Miller, North Amer. Geol. and Pal., 1889, p. 222.— Zittel, Text-Book 

 Pal. (Eastman trans.), 1896, p. 143. — Wachsmuth and Springer, North Amer. 

 Crinoidea Camerata, 1897, p. 406.— Bather, A Treatise on Zoology, III, 

 The Echinoderma, 1900, p. 167. 



Troost's description of this genus is as follows: 



This crinoid though somewhat analogous to the genus Agaricocrinites by the ar- 

 rangement of the plates which compose the body, differs nevertheless generically. 

 The Conocrinites [Alloprosallocrinus] has no oral [anal] aperture like the Agarico- 

 crinites, and is provided with a long proboscis which in one of my specimens is 2\ 

 times larger [longer] than the diameter of the body. Moreover the column is not 

 placed in the bottom of a profound basin, but in the centre of a horizontal plane. 

 These characters separate it from the Agaricocrinites, and as the appearance of the 

 whole if we take the body for a base, is that of a cone, I have given to it the name of 

 Conocrinites. 



generic characters. 



Pelvis [base] hexagonal, divisible into three parts. 

 Costals, [radials] five, hexagonal. 



Intercostals, [anal plate] one, sub-hexagonal, elongated. 

 Scapulars, [primaxils] five, pentagonal. 

 Arms, ten. 



Inter scapulars [interbrachials and anal plates], seven, subhexagonal. 



ALLOPROSALLOCRINUS TUBERCULOSUS (Troost). 



Plate 5, figs. 14, 15. 



Conocrinites tuberculosus Troost, Proc. Amer. Ass. Adv. Sci., II (read 1849), 

 1850, p. 60 (nomen nudum). — Wachsmuth and Springer, Rev. PaLseocri- 

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



Alloprosallocrinus conicus Shumard, Trans. Acad. Sci. St. Louis, II, 1866, p. 353 

 (catalogue name). 



The original description by Troost is as follows: 



The hexagonal pelvis [base] is depressed towards the centre and bears a circular 

 impression of the column. The articulating surfaces of the plates are striated and the 

 alimentary canal [lumen] is circular. The five depressed hexagonal costals [radials] 

 are placed upon five of the sides of the pelvis, and the elongated intercostal occupies 

 the sixth side of it. [?] This intercostal [secondary anal plate] projects beyond the cos- 

 tals [radials]. Between the costals [radials] and scapulars [primaxils] are small plates 

 which penetrate partly the superior edge of the costals [radials] and the inferior edge 

 of the scapulars [primaxils]. Of the five pentagonal scapulars [primaxils], three 



