CHAPTER XVI. 



1856-1858. 



"CONTRIBUTIONS TO THE NATURAL HISTORY OF THE UNITED STATES" 

 ITS IMPORTANCE AS A SCIENTIFIC WORK AND ITS POPULARITY IN 

 AMERICA SPECIAL REPRINT IN ENGLAND, AND FRENCH TRANSLA- 

 TION OF HIS " ESSAY ON CLASSIFICATION " OFFERS OF DR. OSWALD 

 HEER INVITATION TO ACCEPT THE CHAIR OF PALEONTOLOGY IN THE 

 JARDIN DES PLANTES OF PARIS GEOGRAPHICAL DISTRIBUTION OF 

 FRESH-WATER FISHES OF THE UNITED STATES. 



UNDER the direction of Mr. Francis C. Gray, of 

 Boston, a most generous and constant friend of Agassiz, 

 the editorship of an important and costly work on the 

 natural history of North America was undertaken. 

 A subscription list was started as soon as the pro- 

 spectus was issued, in the autumn of 1855, and, to the 

 astonishment and great delight of Agassiz, quickly 

 reached the unexpected number of twenty-five hundred 

 subscribers, the necessary number suggested by the 

 publisher, to insure the success of the publication, 

 being five hundred. The subscription price was twelve 

 dollars per volume, and there were to be ten vol- 

 umes, each volume being entirely independent, except 

 the first two, which were combined in such a manner 

 that they formed a whole. The first two volumes were 

 issued in April, 1858; two more volumes appeared in 



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