BATOCRINID^. 501 



contact with the others. The radial dome plates as large as the orals, and 

 represented in the posterior rays by plates of a first- and second order, in the 

 other rays by a primary plate only. Interambulacral spaces depressed, the 

 plates almost flat. Column proportionally large. 



Horizon and LoealUy. — Keokuk group ; Keokuk, Iowa, and Niota, Ills. 



Tt/jje in the collection of Professor Wetherby. 



Remarks. — Wetherby's description is so general and indefinite, that a 

 satisfactory identification of the species is impossible without a comparison 

 with the type, which is not available at present. 



Agaricocrinus conicus W. and Sp. (nov. spec). 

 Plate XXXIX. Figs. 7, 8. 



Of medium size. Calyx conical, rather high, width and height as 6 to 5 ; 

 in its dorsal aspect irregularly pentalobate, the recess between the posterior 

 rays twice as wide as between the others, and the rays themselves stronger 

 and projecting out farther. Dorsal cup moderately excavated to the middle 

 of the first costals ; plates shghtly convex ; suture lines distinct. 



Basals concealed by the column. Eadials varying in size, the two poste- 

 rior ones larger than the others. First costals considerably wider at the top 

 than at the bottom, their length equal to, or exceeding, the lower width; three 

 of them hexangular, the two posterior ones pentangular. Second costals pen- 

 tangular, as long as the radials and twice as wide ; the posterior ones hexan- 

 gular. The distichals in the posterior rays consist of a single plate, which is 

 as large as the second costals, and axillary ; supporting 2X2 palmars, which 

 are twice as long as the arm plates. Eays with but two arms have two suc- 

 cessive distichals, which in form and size resemble the palmars. Arm facets 

 directed horizontally, contiguous to the second row of arm jilates. Arras 

 broadly spreading, and moderately heavy at their bases. Interbrachials short, 

 rarely reaching the top of the first costals ; the two plates of the second row 

 as long as the first, and almost as wide, the three of the third smaller. First 

 anal plate smaller than the posterior radials, but shorter than the second 

 costals ; the interbrachial plates enclosing the latter rather large, rising to 

 the second costals; they are followed by three as wide but somewhat shorter 

 plates, and numerous others, which together form a flat area with a slight 

 swelling around the anus. Posterior oral as large as the others together, and 

 in contact with them. The food grooves hidden by superimposed interam- 



