Bkede.] Carboniferous Invertebrates. 75 



Concerning the synonymy of the American species of Prod actus 

 there is considerable difference of opinion. As far as our Kan- 

 sas forms are concerned, they have not heretofore been collected 

 and preserved in a manner that indicates the exact range of the 

 different forms, or, indeed, the exact location of the specimens 

 themselves ; in fact, if we are to judge from the localities given 

 in paleontological papers, there has been very little if any ac- 

 curate systematic collecting done in the Coal Measures west of 

 the Mississippi river, except that of Meek in southeastern Ne- 

 braska. As a natural result, the range of the different forms 

 is not known, or even the degrees of variation in the same hori- 

 zon. Under these circumstances, it seems best to be quite con- 

 servative in the number of species recognized until further and 

 better work is done ; however, I am of the opinion that some 

 of the forms here referred to a single species will, on more care- 

 ful study of range restrictions, be separated. This is especially 

 true of P. com, though the data at hand will hardly permit of 

 it now. 



Productus cora. Plate XI, figs. 1-lf. 



Productus coca d'Orbignv, Voy. dans l'Ame*r. M(r. Pal., p. 55, pi. v, ff. 



8-10, (1842 i : Owen, Geol. Rep. Wis., Iowa, and Minn., pp. 103-106, pi. 



v, f. 2, | 1852); White, 13th Rep. St. Geol. Ind., p. 126, pi. xxvi, ff. 1-3, 



(1884): etc. 

 Productus lt/elll de Verneuil, Ly ell's Travels in North America, n, p. 221, 



(1845c Dawson, Acad. Geol., p. 219, f. g, (1855). 

 Productus 8emireticulatU8 Hall, Stanberry's Expl. and Surv. Valley Gt. 



Salt Lake, Utah, p. 411, pi. in, ff. 3, 5. 

 Productus prnffenianus Norwood, Jour. Acad. Nat. Sci. Phil., in, p. 17, 



f. 10, (1854): Meek, Fin. Rep. U. S. Geol. Surv. Neb., p. 163, pi. n, f. 5, 



pi. v, f. 13, pi. vin, f. 10, (1872 c etc. 

 Productus flemmingi Geinitz (non de Verneuil), Garb. u. Dyas in Neb., 



p. 53, pi. iv, f. 5, (1866); etc. 

 Productus calhounianus Geinitz, ibid, (non Swallow). 



Meek's description of Productus prattenianus (in part): " Shell 

 attaining a medium to large size ; breadth generally exceeding 

 the length, especially when the ears are entire; cardinal mar- 

 gin usually somewhat longer than the transverse diameter of 

 the valves at any point farther forward ; anterior and antero- 

 lateral outline regularly rounded. Ventral valve distinctly and 

 rather evenly convex, with or without a shallow mesial sinus ; 



