PLATE XIX. 
Monterey (Middle Miocene) Diatoms. 
Fig. 1. Photomicrograph of slide of partially cleaned diatomaceous shale material 
from the Lompoc quadrangle, X 100. All the larger individuals and 
fragments are Coscinodiscus oculus iridis Ehrenberg. 
Fig. 2. Photomicrograph of slide of diatoms from the Monterey shale at Santa Monica, 
Los Angeles County, Cal , X 00. Nearly all the species shown on this 
slide occur in the diatomaceous deposits in the Santa Maria district. 
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