BRA.CHIOPODS. 43 



Productus biseriatus HALL. 



Productus biseriatus Hall, 1856: Trans. Alabany Inet., vol. IV, p. 12. 

 Productus biseriatus Whitefield, 1882: Bui. Am. Mus. Nat. Hist., No. 3, 



p. 46, pi. vi, figs. 8-1-2. 

 Productus bissriatus Hall, 1883 : Geol. Sur. Indiana, 12th Ann. Rep., p. 



325, pi. xxix, figs. 8-12. 



This shell belongs to the P. punctatm group, but is very 

 small as compared with the typical species. 



Horizon and localities Lower Carboniferous, Keokuk 

 limestone: St. Francis ville ( Clark county); Keokuk (Iowa). 



Productus vittatus HALL. 



Productus vittatus Hall, 1858: Geology Iowa, vol. 1, p. 639. 

 Productus gradxtus Swallow, 1863: Trans. St. Louis Acad. Sci., vol. II. 

 p 93. 



Like P. punctatus of the Coal Measures, and perhaps iden- 

 tical with it. 



Horizon and localities. Lower Carboniferous, Keokuk 

 limestone : Trenton ( St. Louis county ) ; Keoknk ( Iowa ). 



Productus altonensis NORWOOD & PRATTEN. 



Productus altonensis Norwood & Pratten, 1854 : Jour. Acad. Nat. Sci., 

 Phila , vol. Ill, p. 7, pi. i, figs. la-3. 



Like P. arcuatus, but less arched, and with fewer radial 

 costae. 



Horizon andlocxlities Lower Carboniferous, Saint Louis 

 limestone : St. Louis. 



Productus marginicinctus PROUT. 



Productus marginicinctus Prout, 1855: Trans. St. Louis Acad. Sci, vol I, 



p. 43, pi. ii, fig 1. 

 Productus wortheni Hail, 1858: Geology Iowa, vol. I., p. 635, pi . xix, figs. 



la-b 

 Productus marginicinctus Hall, 1858 : Geology Iowa, vol I, p. 664, pi. xxiv, 



figs. 3a-c. 



Shell small, costate, with a marginal thickening. 

 Horizon and localities. Lower Carboniferous, Saint Louis 

 limestone: St. Louis; Keokuk ( Iowa). 



