CYSTIDS AND BLASTOIDS. 135 



Pentremites koninckanus Hall. 



Pentremites ko?iinckanus Hull, 1866: Trans. Albany Inst., vol. IV, p. 4. 

 Pentremites koninckanus Hall, 1858: Geol. Iowa, vol. 1, p. 656, pi. xxii, 

 figs, lla-c. 



Closely related to P. conoideus, but smaller and more 

 globose. 



Horizon and localities. — Lower Carboniferous, St. Louis 

 limestone : St. Louis ; Pella and Oskaloosa (Iowa). . 



Pentremites sulcatus (Rcemrr). 

 Plate xviii, lige. 6a-b. 



Peniatrematites sulcatus Roemer, 1851: Archiv. f. Naturg., Jahrg. xvii, 



Bd. I, p. 354, pi. vi, ligs, lOa-c. 

 Pentremites sulcatus ^hxxmsiva, \So% '. Trans. St. Louis Acad. Sci.,vol. I, 



p. 243. 

 Pentremites missouriensis Swallow, 1863: Trans. St. Louis Acad. Sci., vol. 



II, p. 81. 

 Pentremites sulcatus Etheridge & Carpenter, 1886 : Cat. Blastoidea, p. 165, 



pi. i, tigs. 8-10. 



This species belongs to the P. obesus group, but is much 

 smaller than the typical form. 



Horizon and localities. — Lower Carboniferous, Kaskaskia 

 limestone : Ste. Mary (Ste. Genevieve county). 



Pentremites obesus Lyon 



Pentremites obesus Lyon, 1857; Geol. Sur, Kentucky, vol. Ill, p. 469, pi. 



it, figs. la-d. 

 Petitremites obesus Hall, 1858: Geol. Iowa, vol. I, p. 695, pi. xxv, fig. 15. 

 Pentremites obesus Ethridge & Carpenter, 1886: Cat. Blastoidea, p. 167. 



Calyx subglobose, very large and massive. 

 Horizon and localities — Lower Carboniferous, Kaskas- 

 kia limestone: Ste. Mary ( Ste. Genevieve county ). 



Pentremites pyriformis Say. 



Pentremites pyriformis Say, 1825: Jour. Acad. Nat. Sci., Phila., vol. IV, 



p. 294. 

 Pentremites pyriformis Say, 1825: Zool. Jour., vol. II, p. 314. 

 Pentremites 'pyriformis Troost, 1835: Trans. Geol. Soc. Tenn., vol. I, p. 



229, pi. X, fig. 8. 

 Pentremites pyriformis Hall, 1858: Geol. Iowa, vol. I, p. 693, pi. xxv, 



fig. 6. 

 Pentremites symmetricus Hall, 1858: Geol. Iowa, vol. I, p. 294, pi. xxv, 



fig. 14. 



