ORINOIDS. 175 



Gennseocrinus blends the characters of Actinocrinus, Bato- 

 crinus and Dorycrinus. The three plates in the second anal 

 range of Batocrinns and Dorycrinus, and which are so charac- 

 teristic of these genera as distinguished from the two in 

 Actinocrinus, are in the genus under consideration sometimes 

 present as three pieces, sometimes as only two. As regards the 

 anal structures, a further suppression of the short tube in 

 Gennseocrinus would produce a feature similar to that in Do- 

 rycrinus ; while an extension would give the long ventral tube 

 of Actinocrinus. 



Concerning Blairocrinus, recently proposed, a glance at the 

 type specimens shows that it is in all its details a typical Gen- 

 nseocrinus. The Missouri species, however, is the first occur- 

 rence of the genus above the Devonian. 



Eretmocrinus corbulis Hall. 



Plate xxiii, flg. 10. 

 Actinocrinus corbulis Hall, 1861 : Desc. New Species Palae. Crinoids, p. 1. 

 Actinocrinus corbulis Hall, 1861 : Boston Jour. Nat. Hist., vol. VII, p. 



265. 

 Batocrinus { Eretmocrinus ?) corbulis Meek & Worthen, 1875: Geol. Sur. 



Illinois, vol. V, p. 368. 

 Eretmocrinus corbulis Wachsmuth and Springer, 1881: Proc. Acad. Nat. 



Sci., Phila., p. 347. 

 Batocrinus comparilis MiWer, 1892: Geol. Sur. Indiana, 18th Ann. Rep., 



advance sheets, p. 32, pi. v, figs. 18-20. 



Calyx somewhat like -E/. calyculoides, but much smaller and 

 with nodose plates in the dorsal cup. 



Horizon and localities. — Lower Carboniferous, Lower Bur- 

 lington limestone: Louisiana. 



Eretmocrinus expansus Keyes. 



Plate xxlii, flg. 12. 



Calyx large, about as high as broad. Dorsal cup about 

 one-half the length of the ventral side, rapidly expanding to 

 the arm bases ; basal disk low, shallow, flattened below. Ven- 

 tral side greatly inflated. Surface of dorsal plates slightly 

 convex ; that of the ventral plates covered by large blunt 

 spines and large irregular tubercles. 



Sorizon and localities. — Lower Carboniferous, Lower 

 Burlington limestone: Kinderhook ( Illinois). 



