CRINOIDS. 203 



Calyx large, massive, basin-shaped, and in all respects as 

 in Platycrinns. Surface ornamented by coarse wrinkles. 



Horizon and localities. — Lower Carboniferous, Upper Bur- 

 lington limestone : Ash Grove, Sedalia, Hannibal. 



Usually only the calyx or scattered calycinal plates are 

 found, and therefore the true distinction between this form and 

 Platycrinus is not apparent. Instead, however, of having a 

 small number of arms springing in clusters from each radial, 

 there are long radial extensions, bordered on each side by many 

 arms, as in Steganocrinus. 



Dichocrinus lineatus Meek & Worthbn. 



Dkhocrinus lineatus Meek & Worthen, 1869 : Proc. Acad. Nat. Sci , Phila., 



p. 69. 

 Dichocrinus lineatus Meek & Worthen, 1873: Geol. Sur. Illinois, vol. V, p. 



440, pi. iii, fig. 1. 



Similar to D. striatus, but smaller, and with much finer 

 sculpturing. 



Horizon and localities — Lower Carboniferous, Lower Bur- 

 lington limestone : Hannibal, Louisiana. 



Dichocrinus liratus Hall. 



Dichocrinus liratus Hall, 1861 : Desc. New Species Crinoids, p. 5. 

 Dichocrinus liratus Hall, 1861 : Boston Jour. Nat. Hist., vol. VII, p. 290. 



Calyx of medium size, with broad, shallow basal cup ; ra- 

 dials with a rather prominent angularity running from the lower 

 angles on each side to the base of the free arms. Surface other- 

 wise smooth. 



Horizon and localities. — -Lower Carboniferous, Upper Bur- 

 lington limestone : Ash Grove (Greene county). 



Dichocrinus striatus Owen & Shumard. 



Plate XXV, fig. 8. 



Dichocrinus striatus Owen & Shumard, 1850: Jour. Acad. Nat. Sci., Phila., 

 (2), vol. II, p. 62, pi. vii, fig. 10. 



Dichocrinus striatus Owen &,Sh.nui^v A, 1852: U.S. Geol. Sur. Iowa, Wis- 

 consin and Minnesota, p. 590, pi- vA, fig. 10. 



Calyx rather above medium size, subglobose. Surface or- 

 namented by large rounded ridges running longitudinally from 

 the base to the top of the radials. 



