PRODUCTUS. 155 



Puodi'ctus longispinus, De Koniach. Descript. des Animaux foss. du terr. Carb. 



de Belgique, p. 187, pi. xii, fig. H'*''' and pi. xii bl ", 

 fig. 2, 1843. P. Flemingii, Mon. du genre Productus, 

 pi. x, fig. 2, 1847. 



— lobatus, De Verneuil. Russia and the Ural Mountains, vol. ii, pi. xvi, 



fig. 3 ; pi. xviii, fig. 8, 1845. 



— tubarius, De Keyserling. Reise in das Petschora Land, p. 208, pi. iv, 



fig. 6, 184G. 



— longispinus, Dav. Introduction to British Fossil Brach., pi. ix, fig. 221, 



1853. 



— Wabashensis, Norwood and Pratten. Notice of Producti in the Western 



States and Territories, Journal of the Academy of Nat. Sciences 

 of Philadelphia, pi. i, fig. 6, 1854. 



— splendens, Norwood and Pratten. lb., pi. i, fig. 5. 



— Flemingii, M'Coy. British Palaeozoic Fossils, p. 461, 1855. 



— longtspinus, Dav. Mon. Scottish Carb. Brach., pi. ii, figs. 10 — 19, 1860. 



Spec. Char. Shell very variable in shape, rather small, subcylindrical, usually slightly 

 transverse, rarely longer than wide : hinge-line as long, or a little shorter than the greatest 

 width of the shell ; frontal margin rounded or more or less indented. Ventral valve 

 gibbous, evenly convex, or more or less divided into two lobes by a longitudinal sinus of 

 variable depth, commencing at a short distance from the extremity of the beak ; auricu- 

 late expansions small ; beak incurved, but rarely protruding much beyond the hinge-line. 

 Dorsal valve moderately and uniformly concave, following the curves of the opposite valve, 

 or with a small mesial fold slightly developed towards the front. Surface of each valve 

 covered with numerous small, longitudinal, rounded striae, tolerably regular in their course 

 and respective widths, but augmenting in number by occasional bifurcation and inter- 

 calation. Visceral portions crossed by small, concentric, undulating wrinkles, more developed 

 upon the auriculate expansions ; long tubular spines project from some of the ribs at 

 irregular intervals, more numerous on the ears. Dimensions variable ; two British 

 examples measured — 



Length 9, width 10 lines. 



q 7 



Obs. At least nine or ten so-termed species have been fabricated out of variations in 

 shape of this common, far-spread, very variable species ; but as the study of the types 

 themselves and of a multitude of specimens has clearly shown that every variety or varia- 

 tion is intimately connected by intermediate gradation and inseparable links, we should not 

 be justified in retaining, even as varietal denominations, any of the names enumerated 

 among the synonyms. In Great Britain the shell does not appear to have ever attained 

 much larger proportions than those given above ; and as the term longispinus is the best 

 known and first recorded in the ' Mineral Conchology,' it is retained from the species. P. 

 Flemingii was badly drawn from a very imperfect specimen, nor does Sowerby's figure even 

 do justice to the original specimen, which, along with P. longispinus and spinosus, may 



