60 
PALAEONTOLOGY OF NEW YORK. 
Euomphalus (Phanerotinus) laxus. 
PLATE XVI, FIGS. 8, 9, 16-18. 
Euomphalus laxus, Hall. Descriptions of New Species of Fossils, etc., p. 26. 1861. 
“ “ , “ Fifteenth Rep. N. Y. State Cab. Nat. Hist., p. 54, pi. 6, fig. 2. 1862. 
“ (Ecculiomphalus ?) laxus, Hall. Illustrations of Devonian Fossils: Gasteropoda, pi. 16. 1876. 
Ecculiomphalus comes, Hall. Illustrations of Devonian Fossils: Gasteropoda, pi. 16. 1876. 
Compare Phanerotinus paradoxus, Winchell. Proc. Acad. Nat. Sci. Phila., p. 21. 1868. 
Shell discoid ; lower side broadly umbilicate. Volutions about four, nearly in 
the same plane, the inner ones rising moderately above the plane of the 
outer one, disjoined throughout their entire extent, very gradually and 
regularly expanding from the apex; section circular. Aperture (so far 
as known) subcircular, scarcely expanded. 
Surface marked by crowded concentric strife, which are sometimes regular and 
equal, and on some parts of the shell more closely arranged, and all 
directed a little forward, from the inner side of the volution. 
The greatest diameter of the largest specimen seen, is one inch and five- 
eighths ; the prevailing forms have a diameter of about one inch, while many 
are of smaller size. 
This species differs from any other in this series of strata, except the fol¬ 
lowing one, in the distinct separation of the volutions throughout their entire 
extent. The impressions in stone are strongly marked by the transverse strife, 
which are often crowded in fascicles, and the casts preserve fainter impressions 
of the same markings. 
Recent examinations of the specimens illustrated (ut. cit.) as Ecculiomphalus 
comes have satisfied me that they are imperfect conditions of E. laxus, having all 
the external characters of that species except the inner volutions, which have 
been decollated or removed during the maceration of the shells. I therefore 
propose to unite these two imperfect forms, figs. 8 and 9, with the typical 
forms of the species, figs. IT and 18. 
The Phanerotinus paradoxus (plate 16, fig. 16), described by Prof. Winchell, 
from the Burlington sandstone of Iowa, is an extremely similar form with 
E. laxus. The perceptible difference, on comparing casts of that species, is a 
