III. — Variations and Nomenclature of Bermudian, West 

 Inpian and Brazilian Reef Corals, with notes on various 

 Indo-Pacific Corals. 



By a. E. Yerrill. 



The following observations on a few of the common reef corals of 

 the West Indian fauna are some of the results of my studies of the 

 reef corals continued during the past forty years. During this 

 period I have examined nearly all of the important collections of 

 corals in the United States, including the types of Dana and others.* 

 I have also had opportunities to study, in life, and to collect large 

 series of several of the species here discussed. 



The nomenclature of many of the corals is still unsettled. This is 

 due largely to the natural difficulties of the subject. Perhaps there 

 is no other group in which it is more difficult to determine the true 

 chai'acters of the genera and species and the actual limits of their 

 variations. These difficulties cannot be overcome except by long 

 and careful studies of large series of specimens of all ages and forms, 

 grown under many diverse conditions. Good series of but few 

 species can be found in most museums, even at the present time. 

 Formerly, when most of the species were first described, series of 

 specimens were generally unknown, and most of the species were 

 described from a single specimen, or from very few, and these were 

 often so beach-worn as to be nearly worthless for such a purpose. 



In addition to these natural difficulties, the early literature is very 

 unsatisfactoiy, for numerous species were often confounded under a 

 single name, and a genus was often equivalent to one or several 

 families, or even to the whole order. 



In subdividing the old groups, later writers did not always take 

 sufficient pains to follow the ordinary rules of zoological nomencla- 

 ture, even in some cases when there could have been no reasonable 

 doubt of the identity of the species and genera of the early writers. 



* Among the collections studied by me are those of the Museum of Compara- 

 tive Zoology, which I labelled and catalogued many years ago; those of the U. S. 

 Nat. Museum, including most of Dana's tyjjes ; those of the Museum of Yale 

 University, also including many types of Dana and others ; those of the Ameri- 

 can Museum, New York City; those of Professor Ward of Rochester, N. Y., 

 now in the Field Columbian Museum of Chicago ; of the Peabody Acad. Science 

 Salem, Mass. ; of the Boston Society of Natural History, and many others. 



