Arizona, July 31-1912. Wednesday. Spent the day in Rock Glen and Guy Dale's again. In the Rock Glen at 24 feet below the Encinal Limestone came upon a bed of open sea Platyceras that infest Arthracantha, The oinnids had all gone into debris but the pedipods were wonderfully prolific. Associated I saw Cyrtina hamiltoni; lamington D. mucronata and Johnchusillus stempensis. The section in Rock Glen is as follows:- Upper layer of water face A. vittata Limestone Thin zone of limestone above the shale Blue shale, D. mucronata gone. Coal gone - 3 feet Coal Limestone, 20 inches Blue soft shale n clay. 24 feet from the Platyceras disappears bed at bottom of Rock Glen, Same shale down to Guy Dale's at dam, About 25 feet.