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XVII. 



Elements of Geology. A Text-Book for Colleges and for the General 



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Natural Hiotory in the University of California. Revised and en- 



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 Animal Life, as affected by the Natnral Conditions of Exist- 

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XIX. 



Crayfish : An Introduction to the Study of Zoology. By Professor T. H. 



Huxley, F. E. S. With 82 Illustrations. 12mo. Cloth, $1.76. ' 



XX. 

 Anthropology : An Introduction to the Study of Man and Civilization. 

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XXI. 

 First Principles. By Herbert Spencer. Part I. The Unknowable. 

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 The Principles of Biology. By Herbert Spencer. 2 vols., 12mo. 

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 The Principles of Psychology. By Herbert Spencer. 2 vols., 

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XXIV. 

 The Principles of Sociology. By Herbert Spencet.. 12mo. 

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XXV. 

 The Bata of Ethics. By Herbert Spencer. Being Part I, Vol. I, 

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XXVI. 

 lUnstrations of UniTersal Progress. By Herbert Spencer. 

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