174 PALEONTOLOGY OF NEW JERSEY. 
In this case this one is very much more slender than V. biplicata and par- 
ticularly distinct in being less ventricose above the middle of the volution, 
with a more elevated and less ventricose spire. But among the casts pres- 
ent in the collections of the Acad. Nat. Sci., Phila., and Rutgers College, 
there are numerous individuals occupying an intermediate position between 
these two, which .can scarcely be reconciled with either, while at the 
same time they appear to connect them. Owing to the difference in geolog- 
ical position of V. Abbotti, together with the difference in form mentioned 
above, I see no other course than to consider them as three distinct species, 
especially as one of them appears to be from the base of the Upper Marls. 
The surface characters of all three are similar as far as can be observed - 
from the slight evidence remaining upon the inner surface of the larger 
volutions of the casts. They all appear to have been marked with spiral 
lines and by more or less strongly marked vertical folds. Even the type 
of V. biplicata has evidence of very decided vertical folds, shown when 
looking into the suture between the volutions of the cast. There is also 
much variation in the number and strength of the columellar folds on most 
of the varieties. 
From what I can ascertain from these casts, I see no reason why this 
one should be considered as generically distinct from Volutoderma biplicata. 
There may be reasons why that one should be separated from forms like 
Volutomorpha bella and its congeners, but there certainly can be no generic 
distinction between these ventricose forms. I have therefore placed this 
one under Volutoderma instead of under Volutomorpha, as was done by 
Mr. Gabb. 
Formation and locality: The only two individuals of this species which 
I have seen are in a yellow calcareous marl, or impure limestone, and I 
think they are both from the Timber Creek beds, of the Middle Marls, 
instead of the lower layers in Burlington County, New Jersey, intimated 
by Mr. Gabb. 
