114 CARBONIFEROUS PERIOD. 



Sm-face of the valve marked by fine, regular, rounded striae, some of 

 whicli may be traced continuously from the umbonal region to the front, 

 increasing by implantation, and occasionally coalescing ; somewhat strong, 

 erect spines are usually scattered over the surface, the cardinal boi'der being 

 furnished with numerous sti'ong ones, pointing backward. 



Dorsal valve somewhat uniformly concave ; ears with folds or wrinkles 

 coiTCsponding with those of the other valve ; surface marked like that of 

 the ventral valve, except that it is without spines and concentric folds, and 

 that the lines of growth are rather more distinct upon it. 



Length of a very large specimen, six centimeters ; breadth, six and a 

 half centimeters ; but the average size is about one-thu-d less. 



This species ranges thi-ough the whole Coal- Measure or Carboniferous 

 series ; and if, as now seems probable, P. Icevicostus White, from the Kinder- 

 hook formation in Iowa, is not specifically different, its range is thi-ough all 

 the strata of both the Subcarboniferous and Carboniferous periods. 



Position and locaUti/. — Strata of the Carboniferous period : — near Santa 

 F4 and Zandia Mountains, New Mexico : Piloncillo range near Gavilan Peak, 

 and at the confluence of White Mountain and Black Rivers, Ai-izona : 

 Egan range, thu-ty-five miles south of Egan Pass ; Fossil Hill, Wlute Pine 

 County; Roberts' Creek range. Lander County; and top of Grass Mountain, 

 Ely range, thirty-five miles north of Pioche, Nevada : near Beckwith 

 Spring, Cedar range ; near the top of Mount Nebo ; and upon the west face 

 of OquuTh range, Utah. Imperfect specimens, apparently belonging to this 

 species, were also found at Mountain Spring, Lincoln County, Nevada, and at 

 a locality below Ophir City, Utah, in rocks that I have refeiTod to the Sub- 

 carboniferous pei'iod. As ah'eady shown, it is not improbable that the species 

 ranges from strata of that period upward. 



Productus punctatus Martin, sp. 



Plate VII, fig. 2 a, b, and c. 



Anomites punctatus Martin, 1809, Petrificata Derb., pi. xxxvii, fig. 6 (only). 



Trigonia rugosa Parkinson, 1811, Organic Remains, iii, pi. xii, fig. 11. 



Productus punctatus Sowerby, 1822, Min. Conch., 22. 



Anomites tJiecarius Schlotheim, 1823, Naclitrag zum Petref., ii, 63. 



Productus concentricus Potiez et Micbaud, 1844, Gal. des Moll, du Mus. de Donai, ii, 25. 



Producta punctata Phillips, 1836, Geology of Yorkshire, 215. 



