PREFACE. 
The plates of this atlas were drawn on stone several years ago under the 
direction of Prof. Louis Agassiz. At the request of Mr. Alexander Agassiz 
explanations of the figures have been written out for the accompanying plates. 
In order to fit myself for a better understanding of the anatomy of Astrangia, 
live animals have been used in conjunction with the plates in the preparation of 
the explanations. This part of the work has been done at the Newport Marine 
Laboratory. Since the work came into my hands the publication has been 
delayed in the hope of adding to it something on the development of Astrangia ; 
but, although I have succeeded in getting the ova of this coral, I have thus far 
failed to add anything to the much-needed embryology of this animal. Lest the 
plates should become antiquated, it has seemed best to delay no longer their 
publication, but to print them in the form originally prepared by Prof. Agassiz. 
The reader is reminded that there has been a great advance in histological 
methods since the figures were drawn. In that advance, however, little has been 
added to the knowledge of the minute anatomy of genera of Madreporaria allied 
to Astrangia. 
J. WALTER FEWKES. 
Musrum CoMPARATIVE ZOOLOGY, 
CAMBRIDGE, Mass. 
