194 BULLETIN OF THE BUSSEY INSTITUTION. 
tenella, from the Trenton limestone; O. enatica, from the Hudson River 
group, and Chonetes lata (?), from the upper Silurian; besides Jsotelus gigas, 
and a species of Cythere, from the Trenton; all of which were found to 
consist of carbonate of lime, with only such traces of phosphate as are 
generally found in ¢alcareous shells. 
I am indebted to my assistant, Mr. J. Andrew Henshaw, for aid in 
this research. 
