AN OPERCULATED GASTROPOD FROM THE NIAGARA 
FORMATION OF WISCONSIN. 
EDGAR E. TELLER. 
As many of the gastropods of the Hamilton and the more 
recent formations are known to have been operdilated, it wonld 
not be unreasonable to suppose that some of the earlier forms 
will he found to possess that character. The material of which 
they were composed and the delicacy of the structure of many 
of them was such, however, that it is not likely that in the older 
formations many of them will have left their fossil forms, still 
close investigation should show a few of them. 
Fossil literature of the earlier formations contains hardly a 
single reference to such forms although many specimens should 
he found in the collections of close investigators of such objects. 
The limestones of the Hiagara formation at Racine, Wiscon- 
son, have furnished a few specimens of a fossil that has been 
of doubtful identity, they have always been found in the form 
of a flat impression of what might be supposed to have been that 
of a small and very much crushed and flattened gastropod. 
Ho gastropod of a size that would make such an impression is 
known at the locality, and there are none of the other fossils 
found in the same layers that show any evidence of compres¬ 
sion, neither has it ever been found in any layer except those 
that contain gastropods, these peculiar forms are not numerous, 
neither by the ordinary collector have they been considered 
worth the collecting on account of their evident poor state of 
preservation, but one side of the fossil is known, the other not 
having been as yet recognized. 
Some years since it was suggested to other collectors that they 
were probably that of the operculum of a gastropod but just 
what one unknown, as operculated shells in the formation were 
