26 TOLYZOANS. 



Hemitrypa pateriformis URLICH. 



Hemitrypa pateriformis Ulrich, 1890: Geol. Sur. Illinois, vol. VIII, p. 564, 

 pi: Ivii, figs. 7-7 c. 



Horizon and localities Lower Carboniferous, Keokuk 

 limestone: Keokuk (Iowa). 



Archimedes owenanus HALL. 



Plate xxxiii, fig. 2. 



Archimedes owenanus Hall, 1857 : Proc. Am. As. Ad. Sci., vol. X. p. 178 

 Archimedes owenanus Ulrich, 1890: Geol. Sur. Illinois, vol. VIIL, p. 570, 

 pi. Ixiii, figs. 6-6c. 



Horizon and localities Lower Carboniferous, Keokuk 

 limestone : St. Francisville. 



Archimedes wortheni HALL. 



Plate xxxiii, flg. 1. 



Archimedes wortheni Hall, 1857: Proc. Am. As. Ad. Sci. vol. X., p. 178. 

 Archimedes wortheni Hall, 1858 : Geol. Iowa, vol. I. p. 651, pJ. xxii, figs. 3, 



4a-b,5a-b. 



Archimedes reversa Hall, 1858 : Geology Iowa, vol. I, p. 652, pi. xxii, fig. 2. 

 Archimedes wortheni Ulrich, 1890: Geol. Sur. Illinois, vol. VIII, p. 571, pi. 



Iviii, figs. 8-8a. 



Zoarium large, flabellate, twisted ; often attaining a meas- 

 urement of 20 to 25 centimeters. Axis robust, elongate, fusi- 

 form ; volutions quite regular ; shaft short, abruptly and 

 broadly expanding. Fenestrated portion very broad, with 

 closely set, rigid branches, and consequently very narrow fen- 

 estrules. Zorecial openings small, somewhat elevated. 



Horizon and localities. Lower Carboniferous, Keokuk 

 limestone: Wayland, LaGrange. 



Archimedes swallovanus HALL. 



Archimedes swallovanus Hall, 1857: Proc. Am. As. Ad. Sci., vol. X, p. 



173. 

 Archimedes swallovanus Ulrich, 1890: Geol. Sur. Illinois, vol. VIII, p. 



574, pi. Ixiii, figs. 12-1 2d . 



Horizon and localities. Lower Carboniferous, Kaskaskia 

 limestone : Ste. Genevieve. 



