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REVISION OF THE RODENT GENUS 
APLODONTIA 
By Walter P. Taylor. 
The are of the Mountain Chickadee, ae J eRe Grin- 
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Excavations of Burrows of the Rodent Apindontia, with 
Observations on the Habits of the Animal, by Charles’ 
BERG WARK ORIN eens evs. o Scare cscs Ose eee ee ar ERR EOD -20 
The Growth of Normal and Hypophysectomized Tadpoles 
as Influenced by Endocrine Diets, by P. E. Smith......... 15 
Variability in Soils and its Significance to Past and Future 
Soil Investigations. I. A Statistical Study of Nitrifica- 
tion in Soils, by Dean David Waynick........... ....eseeeee- 
The Registration of Earthquakes at the Berkeley Station 
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At the Lick Observatory £ cation 
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April 1, 1917, to September 30, 1917, by E. F. Oavis............ 25 
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