54 
PALAEONTOLOGY OF NEW YORK. 
side. The absence of a band or sinus on the periphery is, however, a dis- 
tinctive- feature. 
Formation and locality. In limestone below the “ Hydraulic beds” at the Falls 
of the Ohio. Communicated by Dr. James Knapp, of Louisville, Ky., and 
Major S. S. Lyon, of Jeffersonville, la. 
EU OMPHALU S, Sowerby. 
Straparollus, Montfort; Phanerotinus, Sowerby. 
The material for the study of this group of fossils, in my possession, is 
so meagre and unsatisfactory that I am not prepared to express any decided 
opinion regarding the separation of the genera Euomphalus and Straparollus. 
The typical forms of the first, with angulated volutions and depressed spires 
begin their existence in the Calciferous sandstone and continue, with Avide 
interruptions, to the Chemung period. The genus Ophileta of the primordial 
rocks is, in some of its forms, not very different from the Devonian species 
with rounded volutions, which are referred to Straparollus or to Euomphalus 
indifferently. In habit of life and mode of growth the two forms were similar; 
both become septate and decollate in their earlier volutions. In one of the 
angulated forms under consideration, the early volutions were rounded and 
decollated by septation—the angularity being gradually acquired and increasing 
to the aperture. 
I have preferred to adopt the name Euoaiphalus for this group of fossils, 
using the name Straparollus in a subgeneric sense for those with close rounded 
volutions, Avhere the spire rises moderately above the plane of the outer volu¬ 
tion. 
These again, by almost insensible gradations, pass into those forms where 
the volutions are disjoined, constituting the genus Phanerotinus of Sowerby. 
The figures on plate 16 offer examples of these phases, Avhere it becomes 
extremely difficult to draw a line of specific distinction betAveen those with the 
volutions in contact and those Avhere they are perceptibly disjoined. 
