BATOCRINID^. 405 



half its diameter occupied by the column. Eadials large, a little wider than 

 long, the upper face concave, Pirst costals narrower and shorter than the 

 radials, twice as wide as long, upper and lower faces convex. Second costals 

 generally a little longer than the first. Distichals 2X2; followed in the 

 three anterior rays by two rows of two palniars, which support four arms ; 

 in the two posterior rays, in one or both divisions, at one side by one palmar 

 and two post-palmars, at the other by two palmars, a structure which gives 

 to these rays five to six arms, or twenty-two to twenty-four to the spiecies. 

 Arms stout, long, incurving, and biserial from the second free plate ; they 

 gradually increase in width, being at two thirds their length more than twice 

 as wide as at the base, and perfectly flat. Also the plates increase upwards 

 in length, and their outer faces become transversely angular. Interbrachials 

 two; the first very large, the other quite small. Anal plate followed by 

 three and two pieces. The upper row at all five sides is arched by the 

 palmars and post-palmars. Structure of ventral disk not known. 



Horizon and Localiiy. — Upper part of Keokuk group ; Bono, Lawrence 

 Co., Ind. 



Types in the collection of Wachsmuth and Springer. 



Eretmocrinus prsegravis S. A; Milleb. 

 Plate XXXIV. Figs. 9, 10. 



1893. S. A. Miller; Adv. Sheets IStli Rep. Geol. Surv. Indiana, p. 37, Plate 6, Figs. 5 and 6. 



A large, very knobby and robust species, in its ornamentation resembling 

 Lobocrinus TamJeUi ; but the calyx more globular, less distinctly lobed, and 

 with a different arm formula. Dorsal cup saucer-shaped, abruptly spreading 

 from the base up, the plates heavy and covered with large angular knobs, 

 some of which are arranged horizontally, others longitudinally. 



Basals short, forming a hexagon with acute angles; the lower surface 

 slightly excavated for the reception of the column, and pierced by a com- 

 paratively large axial canal. Eadials twice as wide as long, covered with 

 prominent transverse nodes, whose tips reach to the level of the lower 

 margins of the basals. The node of the intervening anal is round, and the 

 plate itself longer than the radials. First costals linear, less nodose than any 

 of the other calyx plates, and sometimes completely flat. Second costals 

 smaller than, the first, depressed pentangular ; their nodes subtriangular. 

 The posterior and antero-lateral rays have but one distichal in their posterior 



