87 
The cast of the interior shows a very decided prismatic appear- 
ance, there being ten well defined prism faces with flat or at times 
slightly concave surfaces. Of these faces that on the inner curv- 
ature of the dorsal surface is the broadest and 1s well defined over 
the body chamber, where the other faces become faint or quite ex- 
tinguished. The body chamber shows a slight constriction at 
about one-half its length. In two of the casts in which the body 
whorl and aperture are entirely preserved, this chamber has a 
length of 45 mm., which is equal to the depth of 6.5 chambers. 
On the exterior the surface 1s ornamented by fine concen- 
tric or horizontal imbricating or engraved lines, which are 
bunched together into low concentric annuli and are crossed ver- 
tically by ridges of about the same size. These are ten in number 
to correspond with the prism angles. Where these cross the an- 
nuli, they are raised into projections which appear for the most 
part to be short, stout and blunt but in some vertical sections of 
the shell are apparently extended, acute and spiniform. The 
exterior markings become fainter on the body whorl, but are 
plainly visible to the aperture, in this respect contrasting to the 
condition of the internal surface. The aperture is sinuous with 
a marked channel on the left lateral margin. 
Dimensions: The specimens observed have an apertural 
diameter of 30 to 40 mm., and bear 16 septa in a distance of 100 
mm., from the last downward. The approximate entire length 
of these shells was 250 mm. 
Locality: Manlius; John D. Wilson, collector and donor.” 
Because of the fragile shale both overlying and underlying, 
and its own unstable character when exposed to the atmosphere, 
exposures of Agoniatite limestone, satisfactory for study, rarely 
occur. Out-crops are common enough, but they are generally 
meagre. ‘Those best known to me are the following: 
At the road side about half a mile southeast of Marcellus vil- 
lage, on both sides of Onondaga Valley from one to three miles 
south of the city line, and in several small ravines south of the 
road between Jamesvile and Manlius. 
In the foregoing paper, I have mentioned only fossils col- 
lected by myself from rock in place in this county. 
