﻿PRODUCTUS. 



103 



of certainty the shell, or casts under description, with P. sub-Iavis, De Kon., of which we 

 have already shown P. Christiani to be a synonym. The difference in the size of the 

 two (?) species is so great and so constant, that upon that ground alone we would feel 

 warranted in expressing some uncertainty as to the identity. It will, therefore, I think, 

 be desirable, for the present at least, to retain for the Upper Devonian shell the designation 

 of prtplonffW,.a8 given by Sowerby in the 'Transactions of the Geol. Soc. of London.' — 

 P. prtelon/jus occurs at Croyde Bay ; also in brown grits at the top of Orchard quarry, 

 parish of Pilton ; at Braunton ; and in the lower Marvvood beds, near Marwood in North 

 Devon, &c. 



Productus scabriculus, Martin. PL XX, figs. 3, 4, 5. 



Productus scabriculus, Martin. Petrif. Derb. p. 8, pi. xxxvi, fig. 5, 1809. 

 Lept^ena scabeicula, pi. 24, fig. 97, 1841. 



Productus scabriculus, Dav. A Monograph of British Carboniferous Brachiopoda, 



p. 169, plate xlii, figs. 5—8, 1861. 



Internal casts and impressions, exactly resembling those of the Carboniferous species, 

 have been mentioned by Phillips as having been found in the Pilton and Marwood beds 

 of North Devon. It will not be necessary to re-describe this shell, since full details will be 

 found in our 'Carboniferous Monograph.' In the Museum of the Geol. Survey may be 

 seen impressions of the interior of the dorsal valve, which are, to all appearance, identical 

 in character with some from the Carboniferous shales of Lanarkshire. 



Productus longispinus? Sow. PI. XX, fig. 7. 



Productus longispinus, Sow. Min. Conch, vol. I, p. 154, pi. lxviii, fig. 1, 1814. 



Imperfect casts of a small Productus bearing much resemblance to certain examples of 

 P. longiqnnus, occur in the Upper Devonian grits at the top of Orchard quarry, near 

 Pilton in North Devon, but it is impossible from the material in our present possession 

 to be quite certain of the identification. These casts are subcylindrical, slightly trans- 

 verse: ventral valve gibbous, evenly convex, but slightly depressed along the middle; 

 ears small ; beak incurved ; dorsal valve concave, following the curves of the opposite one. 

 Surface marked with numerous small longitudinal striae, tolerably regular in their course. 

 Length 6, width 7 lines. 

 In the ' Transactions of the Geol. Soc.,' vol. v, 2nd series, pi. lvi, fig. 7, 

 Sowerby describes and figures under the designation of P. interruptus a small Productus, 



