Louis Agassiz 
Contributions to the Natural History of the United States of America [PDF ebook] 
Second Monograph; In Five Parts; I. Acalephs in General; II. Ctenophorae; III. Discophorae; IV. Hydroidae; V. Homologies of the Radiata; With Forty-Six Plates

Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. Cambridge. The collection of scientific periodicals of the Smithsonian Institution is un questionably the largest on this continent, and but for the wise policy of Prof. Henry, the enlightened head of that establishment, the naturalists of America could not at this time make any investigations involving historical researches. Next to the Smithsonian Institution I have to mention the Academy of Natural Sciences in Philadelphia, the library of which has acquired the highest importance for naturalists, through the liberality with which Dr. Wilson has supplied its wants.