6 



bulx£tin: museum of comparative zoology. 



The remaining eighty-five feet of the Trenton, (390-475 ft.) is a 

 dark, thickly bedded, impure Hmestone with little shale, which on 

 weathering breaks down into a rubbly mass. Fossils are rather 

 conunon in places, but only on weathered surfaces. Strophomena 

 trilohata, Rajimsqulna camcrata, and R. deltoidea are the most common 

 and characteristic fossils, while Hormotoma trcntonensis, Trochonema 

 ttmbilicatiivi, and Streptclasma cornieidum are other abimdant species, 

 these latter forms being "recurrent" from the lower twenty feet of 

 the formation. 



The accompauN-ing table shows the species found, and their vertical 

 distribution. 



