386 THE CRINOIDEA CAMEEATA OF NOETH AMEEICA. 



flattened above ; they are biserial, long, and incurving, — their tips some- 

 times descending to the top of the calyx, — and are composed at their bases 

 of short transverse pieces, which gradually increase in length and width 

 upward. Interradials not numerous, there being from one to three plates 

 at the regular sides, and from four to seven at the anal side including the 

 anals. Ventral disk distinctly asymmetrical, somewhat bulging and higher 

 toward the anterior side, rather flattened posteriorly. Posterior oral con- 

 spicuous, large, and central in position; the anal tube excentric and often 

 curving outward. Column round ; the axial canal small and pentangular. 



Distribidion. — Restricted to the Burlington limestone and Keokuk group, 

 and, so far as known, confined to America. 



Ti/jye of the genus : Eretmocrinus magnificus Lyon and Cass. 



Remarks. — Meek and Worthen treated Eret^nocrinus as a subgenus of 

 Batocriniis, and added several forms which do not belong to it. It differs 

 from Batocriniis in the broad, truncated, and projecting basals, the long, paddle- 

 shaped, and incurving arms, their arrangement, the asymmetry of the ventral 

 disk, and in the excentric position of the anal tube, — all of which are good 

 distinctive characters. 



Eretmocrinus magnificus Lyox and Cass. 

 Plate XXXVII. Fig. 3. 



1859. Ltos and Cassedat; Amer. Journ. Sei., Vol. XXVIII., p. 241. 

 1881. W. aud Sp. ; Revision Palaiocr., Part 11., p. 173. 



(Not Ereimocriims magnificus Quejtstedt ; Handb. der Pateont. (Auflage 3), Plate 77, Kg- 11 = 



Batorrhms grandis) . 

 Syn. TSretmocrinus Igoimiius S. A. JIiller; Adv. Sheets 17tli GeoL Rep. Indiana, 1S91, p. 59, Plate 

 10, Figs. 3 and 4. 



Calyx higher than wide, biturbinate ; the dorsal cup frequently shorter 

 than the ventral disk ; broadly truncate at the base ; the sides concave, 

 spreading abruptly near the arm bases. The radials and brachials in well- 

 marked specimens are keel-shaped, with a prominence or node in the centre 

 of each plate, in others they are simply convex ; the interbrachial plates, in 

 most of the specimens, are perfectly flat. 



Base short, extended into a broad rim, which projects considerably 

 beyond the radials ; it has a shallow depression at the bottom, and a some- 

 what deeper one for the reception of the column, which occupies less thah 

 half the diameter of the lower face. Eadials more than twice as wide as 

 long. First costals quadrangular, about half the size of the radials; the 



