CARBONIFEROUS PERIOD. 113 



Position and locality. — Strata of the Carboniferous period : — near Bear 

 Spring, Camp Wingate, and near Santa Ft;, New Mexico : Camp Cotton- 

 wood, old Mormon road, Lincoln County, and top of Grass Mountain, Ely 

 range, thirty -five miles north of Pioche, Nevada : head of Partridge Creek ; 

 near Bill "VVilHams's Mountain ; Tenney's Ranch ; Kaibab Plateau ; head 

 of Dry Fork, and Kanab Canon (Aubrey limestone), Arizona: crest of 

 Hunicane Hill, near Toquerville, and Meadow Creek, south of Fillmore, 



Utah. 



Productus Prattenianus Norwood. 



Plato VII, fig. 1 a, h, and c. 



Prodtictiis cora Owen, 1852, Geol. Report Iowa, Wisconsin, and Minnesota, pi. v, fig. 1 



(not d'Orbigny). 

 Productus semireticulatuit Hall, 1852, Stansburj's Report Great Salt Lake, 411 (not 



Martin, sp.). 

 Productus Prattenianus Norwood, 1851, Jour. Acad. Nat. Sci. Pliila., n. s., iii, 17. 

 Productus wquicostatus Shumard, 1855, Geol. Report Missouri, 201. 

 Productus cora Marcou, 1858, Geology of North America, pi. vi, figs. 4 and 4^ (not 



d'Orbigny). 

 ? Productus Iwvicostus White, 1860, Jour. Bost. Soc. Nat. Hist., vii, 230. 

 Productus Flemingii Geinitz, 1866, Carbonformat. und Dyas in Nebraska, 52 (not 



Sowcrby, 1814). 

 Productus Calhounianus Geinitz, 1866, ib., 81 (not Swallow, 1858). 

 Productus Koninchianus Geinitz, 1866, ib., 53 (not de Verneuil, 1845). 

 Productus Prattenianus Meek, 1872, U. S. Geol. Surv. Nebraska, 163. 



Shell usually of medium size, but sometimes quite large ; breadth gen- 

 erally greater than the length, if the latter be measiu'ed in a straight line 

 fi-om hinge to front ; hinge in most cases longer than the greatest width of 

 the body of the shell ; lateral and front margins regularly and continuously 

 rounded ; ears prominent, thin, and generally broken off in the embedding 

 rock ; mesial fold and sinus wanting. 



Ventral valve somewhat uniformly convex, but in some old shells there 

 is a greater or less mesial flattening of the visceral region ; umbonal region 

 gibbous as a rule, but in rare cases depressed ; beak hardly projecting over 

 the cardinal border ; ears marked by strong wrinkles, which are continuous 

 with similar faint ones that pass up from each side toward the visceral 

 region of the valve, and in rare cases meeting at the middle, the wrinkles 

 ending posteriorly at the cardinal margin, upon which they produce an 

 appearance similar to that, of a cui-tain gathered upon a cord. 

 8 P . ■ 



