ADVERTISEMENT. 
The present publication, though the mere fragment of a memoir many 
years ago undertaken by the eminent naturalist, Professor Agassiz, is at last 
offered to biologists in its imperfect state, in the belief that even in this form, 
and at this late day, it will be welcomed by many students who would be reluct- 
ant to have the fruit of worthy labor wholly lost to the world. 
The scope of the brief abstract, and the circumstances occasioning the 
unusual delay in its appearance, will be sufficiently explained by the following 
statement received from Mr. Alexander Agassiz: 
“The plates of Astrangia were drawn by Mr. Sonrel, under Professor 
Agassiz’s direction, as far back as 1849. The material was collected during 
the first dredging trip undertaken by Professor Agassiz under the auspices of 
the United States Coast Survey. Professor A. D. Bache, then Superintendent 
of the Coast Survey, invited Professor Agassiz to join the United States Coast 
Survey steamer ‘Bibb,’ commanded by Lieutenant Charles H. Davis, after- 
wards Rear Admiral, and to undertake a dredging trip in the vicinity of 
Nantucket. Among other material, numerous bunches of Astrangia were 
collected by the ‘Bibb.’ These were kept alive at Cambridge for nearly a 
year. During that time some drawings were made towards illustrating the 
anatomy of the genus. The completion of the memoir was delayed in the hopes 
of adding the developmental history of the genus, but after the first year of 
preparation Professor Agassiz never again had the opportunity of taking up 
the subject. The plates therefore remained unpublished in the hands of the 
Smithsonian Institution. The last year of his life Mr. Louis F. Pourtalés under- 
took the completion of the work at the Newport Marine Laboratory, but he only 
brought together the necessary materials, and left neither notes nor drawings 
for publication. At the request of Professor Spencer F. Baird, Secretary of the 
Smithsonian, Mr. J. Walter Fewkes has written an explanation of the plates 
to make them available to students of marine invertebrates.” 
8. P. LANGLEY, 
Secretary of the Smithsonian Institution. 
Smitusontan InstiTUTION, 
Wasuineron, D. C., February, 1889. 
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