PALAEONTOLOGY OF IOWA. 553 



8capliiociinns dicliotoiims ( n. s.). 



BODY small. Basal and subradial plates small. First radial 

 plates pentagonal, wider than long. Second radials pentago- 

 nal, much longer than wide, rounded and contracted in the 

 middle, swelling out at the extremities Arm-plates resting 

 on the upper sloping sides of the second radial plate : arms 

 double from their origin, and bifurcating upon the tenth, 

 eleventh or twelfth plate above, and thence continuing sim- 

 ple to their extremities. Plates wedgeform, and furnished 

 with tentacula on the broader margins. Anterior ray simple 

 to the twelfth plate, where it bifurcates. 



SURFACE roughly granulated. 



FIG. 72. 



The accompanying diagram illustrates the structure of the 

 body and several of the arms as far as the first bifurcation, 

 showing the simplw anterior ray and the arms from the antero- 

 lateral ray, of which one does not bifurcate, so far as observed . 

 The base is too minute to admit of the lines of subdivision. 



Geological formation and locality. In the Burlington limestone : Quiucy, 

 Illinois. 



Poteriocrinus calycnlus ( n. s.). 



PLATE IX. FIG. 6 a, b, c. 



BODY small, subturbinate or urn shaped. Basal plates small, 

 slightly depressed towards the inner margin, extending al- 

 most horizontally for half their length, and turning upwards 

 in 'the line of the lateral angles. Subradials wider than long; 

 three hexagonal and two heptagonal. Radial plates short, 

 pentagonal, truncate or slightly emarginate above, abruptly 

 bent inward at the side so as to leave a broad groove along 

 the suture line. The two anal plates preserved are pentagonal. 



SURFACE finely granulate. Column small, 

 [low A SURVEY.] 70 



