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. 
Euomphalm Decewi, Billings. Canadian Journal, p. 358. July, 1861. 
“ Conradi, Hall. Fourteenth Rep. N. Y. State Cab. Nat. Hist., p. 107. 1861.* 
“ Decewi, B., Meek : Geol. Surv. Ohio: Pal., vol. 1, p. 220, pi. 19, figs. 3 a, b ; and pi. 20, fig. 1. 1873. 
“ “ Hall: Illustrations of Devonian Fossils: Gasteropoda, pi. 15. 1876. 
Shell discoid, upper side moderately concave or sometimes nearly flat, the 
lower side broadly and deeply concave; jieriphery moderately convex or 
nearly flat, 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 of 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 strise of growth. The 
fossil 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 note by the Secretary of the Board of Regents, preceding the Fourteenth Report, is as follows: “ The 
Fourteenth Report is published, August, 1861. Some copies of the Descriptions of New Species [of Fossils], 
by Prof. Hall, were distributed in July.” 
