EXPLANATION OF THE ILLUSTRATION 
Pirate XXXVIII. Upper. Swallow Cave, Slab Cave 
and Tau Cave (second, third and fourth from left, 
respectively) are located on the face of this cliff in 
Cave Valley, Chihuahua, Mexico. Lower. A view 
of the interior of Olla Cave, Chihuahua, Mexico, 
showing a granary in the foreground. 
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