LOWEE CARBONIFEROUS FOSSILS. 531 



of the shell, which falls away quite rapidly on either side, giving rise to 

 large produced and flattened ears. This is a variable feature, however, 

 and the lateral margins may meet the hinge line at nearly right angles. 



Dorsal valve only slightly convex, but geniculate toward the anterior 

 margin. 



Surface nearly smooth, marked by numerous gentle rugosities, and by 

 very fine, confused, radiating stria;, which may be the result of exfoliation 

 joined with shell structure. 



The dimensions of a slightly undersized auriculate specimen, figured 

 on PI. LXVIII, fig. 10c, are: Length, 25 mm.; width at hinge line, 44 mm.; 

 width a little in front of hinge line, 25.5 mm. The largest specimen 

 observed, a spreading individual, with a nearly vertical posterior outline, 

 measures 54.5 mm. in length; width probably about the same. 



Formation and locality: Madison limestone, limestone bluff south 

 side of Soda Butte Creek, northwest of Abiathar Peak, Absaroka Range; 



J. P. Iddings. 



PRODUCTUS Sowerby, 1814. 



Productus scabriculus Martin. 

 PI. LXIX, figs, la, lb, 1c, Id, 



Anomites scabriculus Martin, 1809: Petrefacta Derbiensia, p. 8, PI. XXXVI, fig. 6. 

 Productus scabriculus Norwood and Pratten, 1854: Jour. Acad. Nat. Sci. Philadelphia. 



(2), Vol. Ill, p. 17. Marcou, 1858: Geol. North America, p. 47, PI. V, fig. 6. 



Newberry, 1861: Ives's Rept. Colorado River of the West, Pt. II, p. 125. 



?Geiuitz, 1866: Carbon, und Dyas in Nebraska, p. 54. 



This form was at first identified with Productus neivberryi Hall. It 

 closely resembles the figure of P. neivberryi (Pal. New York, Vol. VIII, 

 Pt. I, 1892, PI. XVII, fig. I) 1 (non figs. 2 and 3), but a comparison with 

 specimens made me doubt the correctness of the identification. I have 

 been able to examine a large series of P. neivberryi from Bagdad, near 

 Medina, Burbank, and other localities in the Cuyahoga shale, in Medina 

 County. It is perhaps the most abundant form at these localities next to 

 Chonetes illinoisensis ? and Hall's figure seems to me quite misleading in 

 regard to the surface ornamentation. The figures show numerous close-set 



•Figs. 2 and 3 of this species seem to be different from P. newherryi. The surface ornamentation 

 does not appear, hut it is a much more profoundly arched shell, and comes from a different geologic 

 horizon. 



