168 CRINOIDS. 



Agaricocrinus wortheni Hai.l. 

 Agaricocrinus wortheni Hall, 1858: Geol. Iowa, vol. I, p. 419, pi. xvi, fig.l. 



Calyx closely resembling that of A. atnericanus, from which 

 it is most readily distinguished by the shorter radials, hexa- 

 gonal, instead of quadrangular, first costals, and larger second 

 costals. 



Horizon and localities. — Lower Carboniferous, Keokuk 

 limestone : Wayland (Clark county) ; Keokuk (Iowa ). 



Agaricocrinus americanus (Roembr). 



Plate xxii, flgs. 8-ab. 

 Amphoracrinu,s america7ius Roemer, 1850 : Leth. Geol., vol. II, p. 250, tab. iv, 



tig. 15. 

 Agaricocrinus iuberosus Hall, 1858 : Geol. Iowa, vol. I, p. 617, pi. xvi, fig. 2. 

 Agaricoo-inus hullatus Hall, 1858: Geol. lowa, vol. I, p. 562, pi. ix, fig3. 



lla-c. 

 Agaricocrinus excavatiis Hall, 1861: Boston Jour. Nat. Hist., vol. VIII, 



p. 282. 

 Agaricocrinus a^nericanus Shnm&Ta, 1865: Trans. St. Louis Acad. Sci., vol. 



II, p. 351. 

 Agaricocrinus nodosus Meek & Worthen, 1869 : Proc. Acad. Nat. Sci., Phila,, 



p. 167. 

 Agaricocrinus nodosus Mee^ & WoTthen, 1873; Geol. Sur. Illinois, vol. V, 



p. 387, pi. X, fig. 7. 

 Agaricocrinus americanus Wachsmuth & Springer, 1885: Proc. Acad. Nat. 



Sci., Phila., p. 285. 



Calyx pyramidal,'pentalobate, wider than high ; dorsal con- 

 cavity large and moderately deep. Surface unmarked except 

 the nodose plates on the oral side. Basals three, small, nearly 

 equal in size. Eadials rather small. First costals rectangular, 

 and considerably smaller than the radials ,- the second much 

 larger, pentagonal, wide ; and followed by one or more some- 

 what smaller pieces ; subsequent brachials very short, but very 

 wide, forming a double series of interlocking plates. Arms 

 stout, long, regularly tapering to the ends ; pinnules long. Sur- 

 face smooth dorsally ; nodose ventrally. 



Horizon "and localities. — Lower Carboniferous, Keokuk 

 limestone: Wayland (Clark county.) 



