118 CARBONIFEROUS PERIOD. 



Productus longispinus Sowerby. 



Plate VIII, lig. 5 a, b, c, and d. 



Productus longispinus Sowerby, 1S14, Mineral Conchology, i, 154. 



Productus Flemingii Sowerby, 1814, ib., 154. 



Productus spinosits Sowerby, 1814, ib., 155. 



Productus lohatus Sowerby, 1814, ib., iv, IG. 



Producta setosa Phillips, 1836, Geol. of Yorksbire, ii, 214. 



Productus longispinus de Koiiiuck, 1843, Anini. Foss. Terr. Carb. Belg., 184. 



Productus capacii d'Orbiguy, 1843, Voyage dans I'Am^rique M6rid., iii, 50. 



Productus tubarius Keyserling, 1846, Reise in das Petschora Land, 208. 



Productus longispinus Davidson, 1853, Int. Brit. Foss. Brach., pi. ix, 221. 



Productus Wabasliensis Norwood and Pratten, 1854, Jour. Acad. Nat. Sci. Phila., n. s., 



iii, 13. 

 Productus splendem Norwood and Pratten, 1854, ib., 11. 

 Productus Orbignyanus Geinitz, 1866, Carbonformat. und Dyas in Neb., 56 (not de 



Koniuck, 1848). 

 Productus liorridus Geinitz, 1866, ib., 55 (not Sowerby, 1822). 

 Productus longispinus Meek, 1872, U. S. Geol. Surv. Nebraska, 161. 



Shell small, almost always broader than long, usually broadest at tbe 

 liinge-line; ears distinct, a little reflexed, sometimes very prominent, each 

 antero-lateral border regularly rounded from the base of the ear to the 

 mesial sinus. 



Ventral valve very gibbous, greatest convexity behind the middle, where 

 the antero-posterior curvature is sometimes so abrupt as to make the hinder 

 portion almost perpendicular with the plane of the margins, but the curva- 

 ttu'e is generally more regular, carrying the lunbonal region to the rear of 

 the hinge-hne; beak small, slightly prominent, barely projecting over the 

 cardinal margin; mesial sinus usually broad and distinct, but sometimes 

 almost obsolete; postero-lateral slopes almost perpendicular with the ears. 

 Siu-face of the valve marked by fine, radiating, rounded striae, which are 

 variable in their distinctness and size in different shells as they are also in 

 different varieties, more distinct on the ventral than on the dorsal valve, gen- 

 erally obsolete on the imabonal region of both valves; stria; crossed by fine 

 concentric wrinkles, which are distinct in some specimens but obsolete in 

 others; fine concentric lines of growth are also to be seen under a lens; spines 

 strong, erect, long, scattered over the surface somewhat uniformly, but from 



