CRINOIDS. 19;^ 



Strotocrinus regalis (Hall). 



Plate xxiv, flfi. 9. 



Actinoci-inus regalis Hall, 1S59 : Geology Iowa, vol. I, Supp., p. 38. 

 Aciinocrinus speciosus Meek & Worthen, 18G0 : Proc. Acad. Nat. Sci , 



Pblla., p. 38. 

 Strotocrinaa regalis Meek & Worthen, 1866: Geol. Sur. Illinois, vol. II, 



p. 192, pi. xvi. fig3. 6a-b. 

 Strotocrinus bloomfieldensis Miller, 18S0 : Jour. Cincinnati Sec. Nat. Hist., 



vol. 11, p. 258, pi. XV, figs. 6-6a. 

 Strotocrinus bloomfieldensis Miller, 1881: Jour. Cincinnati Soc. Nat. Hist., 



vol. IV, p. 7, pi. i, fig. 6. 

 Strotocrinus regalis Keyes, 1890: A.(n Naturalist, vol. XX[V, p. 224, pi. 



viii, fig. 7, 



Calyx very large, massive, obconic, with a broad horizon- 

 tal rim around the region of the arm bases. Ventral parts flat, 

 greatly extended laterally. Stem circular in cross-section, long, 

 rather small, with a pentagonal central canal. Basals very 

 large, forming a deep, truncated basin. Eadials very large, 

 hexagonal, much longer than wide. First and second costals 

 of equal, size ; other brachials to the twelfth order large, firmly 

 anchylosed to the lower pieces of the free arms for a consider- 

 able distance, and forming a wide decagonal, horizontal exten- 

 sion around the peripheral margin of the calyx. Tegmen com- 

 posed of a large number of small, subspinous plates ; with a 

 subcentral perforation. Arms 100 to 150 in number, slender 

 and fringed with long pinnules. Surface of the dorsal cup 

 highly ornamented by a complex series of sharp, elevated ridges, 

 radiating from the center of each plate to the centers of the 

 adjoining pieces, the whole dividing the area into intricate sets 

 of concentric triangles. 



Horizon and localities. — Lower Carboniferous, Upper Bur- 

 lington limestone : Ash Grove, New Bloomfield, Hannibal. 



This magnificent form is seldom found in good preservation. 

 The crown often attains a vertical measurement of 10 or 12 

 centimeters and a width of even greater dimensions. There 

 are probably but two species as yet known of this genus; 

 though half a dozen or more specific names have been pro- 

 posed for different individuals from various localities. ;S^. 

 Bloomfieldensis, described by Miller from casts found at Kew 



