458 THE CRINOIDEA CAMEEATA OF NORTH AMERICA. 



Keokuk, and generally crushed. Good calyces are found in Barren Co., 

 Ky., and very excellent specimens with arms came from Indian creek, Mont- 

 gomery Co., Ind. 



Type in the (Worthen) Illinois State collection, Springfield. 



Remarks. — It is only in very large specimens that every arm is paired, 

 single arms being most generally represented in one or more rays. It is also 

 interesting to note that our largest specimen not only has the arms all in 

 pairs, but has in both antero-lateral rays four pairs instead of three, — the 

 only exception among seventeen specimens. 



Dorycrinus cornigerus (Hall). 



Plate XLII. Figs. 5 and 6, and Plate XLIII. Fig. 5, and Plate XLIV. 



Figs. 6 and 7- 



1833. Actinocriims cornigerus — Hall ; Gcol. Hep. Iowa, Vol. I., Part II., p. 576, Plate 9, Figs. Via, b, c, 

 and ibid., Suppl., Plate 3, Fig. 4. 

 (Not Aclinocrinus cornigerus Lyon and Cass., 1S59 = Jorocrinus kentucMensis). 

 1873. Lort/crinus cornigerus — Meek and Wokthen; Geol. Rep. Illinois, Vol. V., p. 380. 

 1881. Dorycrinus cornigerus — W. and Sp. ; Revision Palfeocr., Part II., p. 179 (Proceed. Acad. Nat. Sci. 

 PUila., p. 353). 

 Syn. Aclinocrinus iinaricatus Hall; 1S59, Suppl. Geol. Rep. Iowa, p. 11. 

 Syn. Aclinocrinus decornis Hall ; 1859, ibid., p. 13. 



Calyx wider than high ; the ventral disk as high as the dorsal cup. The 

 latter turbinate, broadlj' truncated at the base, spreading rather rapidly from 

 the top of the basals to the top of the costals, and thence more abruptly to 

 the arm bases. The distichals and palmars form very prominent lobes with 

 well defined sinuses between the arm-bearing plates. Plates smooth and 

 almost flat, the suture lines but very slightly grooved. 



Base large, the rim almost circular and without notches at the sutures ; 

 almost flat on the bottom, the column facet occupying but one fourth of its 

 diameter. Form of radials variable ; in some specimens almost as long as 

 wide, in others nearly twice as wide as long, the upper face excavated. Cos- 

 tals rather large ; the first quadrangular, once and a half as wide as long, the 

 lower face convex ; the second wider but not longer than the first ; the sides 

 spreading abruptly upwards ; the three anterior ones generally heptangular, 

 those facing the posterior side hexangular, the sloping upper sides straight, 

 contrary to those of D. quinquelobiis, in which they are excavated. The pos- 

 terior rays, and occasionally the anterior one, have two axillary distichals, 

 which on each side support a moderately long palmar, the latter ray in the 



