GASTEROPODA. 55 



Under such conditions it is certainly impracticable to indicate a strict 

 generic separation, and, in the present mode of stating similar questions, I see 

 no good reason why all these forms may not be included under one generic 

 term, indicating the others as of subgeneric value. 



EUOMPHALUS DECEWI. 



PLATE XV, FIGS. 1-8. 



Eiwiiiphaliis Decern, Billings. Canadian Journal, p. 358. July, 1861. 



" Cwiradi, Hall. Fourteenth Rep. N. Y. State Cab. Nat. Hist., p. 107. 1861 * 



" Decern, B., Meek : Geol. Surv. Ohio: Pal., vol. 1, p. 220, pi. 19, figs. 3 a, b ; and pi. 20, fig. 1. 1873. 



" " Hall: Illus' rations of Devonian Fossils: Gasteropoda, pi. 15. 1876. 



Shell discoid, upper side moderately concave or sometimes nearly flat, the 

 lower side broadly and deeply concave ; periphery moderately convex or 

 nearly ilat, and slightly oblique to the plane of the shell : sometimes, in 

 the casts of young shells, gently rounded from the upper margin to the 

 edge ef the umbilical depression. Volutions three or four (rarely more 

 than two or three preserved in the casts), inner ones rounded, gradually 

 becoming depressed on the upper and lower sides. The periphery, at 

 first rounded and undefined, becomes more flattened and distinctly lim- 

 ited by a defined angularity above and below, becoming more flattened 

 towards the aperture ; the upper side being gently depressed, while the 

 lower side gradually assumes a more abruptly concave aspect, forming a 

 broad umbilicus. Aperture unknown ; section' of the outer volution sub- 

 quadrilateral, or triangular with the inner angle truncated. 



Surface (in young specimens) marked by fine elevated striae of growth. The 

 foasU has a diameter of from one to four inches or more. 



This species, originally described by me as E. Conradi, occurs in several 

 localities in Western New York, and notably at Stafford and Batavia, where 

 casts of the interior are common. Among all those examined from these local- 

 ities I have seen but one or two which retain any portion of the shell. In the 



* A not.- by the S,-,retary of the Board of Regents, preceding the Fourteenth Report, is as follows: " The 

 rtmrteentfa Report is published, August, 1861. Some copies of the Descriptions of New Species [of Fossils], 

 by Prof. Hall, were distributed in July." 



