TROOST 's CRICOIDS OF TENNESSEE — E. WOOD. 



57 



It also differs in minor features of the surface ornament. A com- 

 parison of the types might show them to be of the same species. 



Formation and locality. — Hamilton. Falls of the Ohio. 



Cat. No. 39912, U.S.N.M. 



Suborder BATOCRINOIDEA Bather. 



Family COELOCBJNIDyE Bather. 

 Genus AGARICOCRINUS Troost. 



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

 (nomen nudum); MSS., 1850.— Hall, Geol. Rep. Iowa, I, Pt. 2, 1858, p. 

 560.— Shumard, Trans. Acad. Sci. St. Louis, II, No. 2, 1866, p. 351.— 

 Meek and Worthen, Geol. Rep. Illinois, II, 1866, p. 210. — Wachsmuth 

 and Springer, Proc. Acad. Nat. Sci- Phila., 1878, p. 350; Rev. Palseo- 

 crinoidea, II, 1881, p. 109.— Zittel, Text-Book Pal. (Eastman trans.), 1896, 

 p. 143.— Miller, Bull. No. 12, Illinois State Mus. Nat. Hist. 1897, p. 9.— 

 Wachsmuth and Springer, North Amer. Crinoidea Camerata, 1897, p. 

 486. — Bather, A Treatise on Zoology, III, The Echinoderma, 1900, p. 167. 



Amphoracrinus Roemer (not Austin), Leth. Geognostica, 1855, p. 250. — Hall^ 

 Boston Jour. Nat. Hist., 1861, p. 280. 



The original description is as follows : 



This crinoid differs so much in its form from the generality of these fossils, that even, 

 without regard to the peculiar combination of its plates, its form alone would entitle 

 it to rank as a new genus. The column being attached in the bottom of an inverted 

 basin and all the plates proceeding from the pelvis which forms the center of the basin, 

 running downward, give it the appearance, when a stem is attached to it, of a parasol 

 or mushroom (agaricus, whence its name). The coronal integument which surrounds 

 this basin is composed of hemispherical tubercles, and has the form of a cone or of a 

 pentagonal pyramid. 



generic characters. 

 Pelvis [base] hexagonal divisible into three parts. 



Column cylindrical with striated articulating surface and pentapetalous alimentary 

 canal [lumen]. 



Costals [radials and anal plate] six, hexagonal. 



Scapulars [first primibrachs] five, pentagonal. 



Interscapulars [interbrachials] seven, elongated subhexagonal. 



Observations. — This description of the genus was published by Hall 

 [1858, p. 560] in connection with his description of Agaricocrinus 

 bullatus from Burlington, Iowa. On page 617 of the same report he 

 publishes a description of Agaricocrinus tuherosus, using as a type a 

 specimen from Keokuk, Iowa, merely referring in his synonymy to 

 the description of Troost which was in his hands at the time. Appar- 

 ently none of the specimens in Doctor Troost's collection agree with 

 Hall's A. tuherosus, as noted in the following descriptions of the 

 species, but A. tuherosus is the species mentioned by Hall as the type 

 of the genus, and according to the accepted rules of priority it must 

 remain so, although the name now applies to a different species from 

 the one designated by the author of the genus. 



