628 



GEOLOGICAL SURVEY OF IOWA. 



Cjatliocrinus magister ( n. s.). 



PLATE XVIII. FIG. 2 a, b, and 3 a, b. 



CALYX large; the base broad and spreading, wider than 

 high, projecting beyond the column from three-eighths to 

 half an inch, the centre marked by a large obtusely pen- 

 tagonal opening : subradial plates large and thick. Radial 

 plates large and strong, being in one specimen an inch and 

 a quarter wide and three-fourths of an inch long, while the 

 thickness on the upper articulating face is more than half an 

 inch. 



COLUMN very large, obtusely pentangular with the sides 

 concave, composed of alternating thicker and thinner joints, 

 the thicker ones sometimes nodose at the angles. 



The specimens described are the basal plates with a fragment of the column at- 

 tached, and a separate fragment of a similar column. Another specimen, not figured, 

 preserves the plates of the body and a piece of the column. Some other large frag- 

 ments, and roots of large size, apparently belong to this species. 



Fig. 2 a. The basal plates and fragments of column attached. 



Fig. 2 b. Base of the same specimen. 



Fig. 3 a. Fragment of separate column of apparently the same species. 



Fig. 3 b. Transverse section of the column, showing a large obtusely pentagonal foramen. 



Geological formation and localities In the Keokuk limestone : Keokuk, 

 Iowa ; and in the same rock opposite Madison in Illinois. 



GENUS FORBESlOCRIflUS (DE KONINCK & LE HON). 



FIG. 100. 



"GENERIC FORMULA. 

 Basal pieces, 6. 

 Radial pieces, 4X5. 

 Interradial pieces, 12 or 13 X 4. 

 Anals unknown. 

 Interaxillaries, 3 known. 

 N timber of arms, 50 to 60. 





