GEOLOGY: T. W. VAUGHAN 
95 
THE RESULTS OF INVESTIGATIONS OF THE ECOLOGY OF 
THE FLORIDIAN AND BAHAMAN SHOAL- WATER CORALS 
By Thomas Wayland Vaughan 
U. S. GEOLOGICAL SURVEY. WASHINGTON. D. C. 
Received by the Academy. January 27, 1916 
Many of the most important principles of coral ecology were long ago 
recognized and clearly formulated by Darwin and Dana. More re- 
cently Klunzinger, Pourtales, Moseley, Alexander Agassiz, Verrill, 
Stanley, Gardiner, von Marenzeller, Duerden, Wood-Jones, and others 
have made important contributions. 
The coral faunas which live in water less than 25 fathoms deep in 
coral-reef regions are separable into two subfaunas according to their 
ability for withstanding violently agitated water. These are (1) the 
strong, firmly attached, usually massive forms which can withstand 
breakers and the pounding of the surf; and (2) the weakly attached and 
branching forms which can survive only in quiet water. The forms 
requiring quiet water are further subdivisible according to their capacity 
to resist the deleterious effects of silt. A species of massive growth 
habit often will also live in quiet water. In some instances the same 
species of branching coral may be represented in both quiet and rough 
water, but the colonies in the rough water have shorter and stouter 
branches, responding to the environment by strengthening their skeletal 
structures. Massive, large, head-like corals, such as Orbicella annularis, 
form the strong frame-work of the reef while in the interspaces between 
the heads many colonies of species of smaller size grow and other 
organisms are present in greater or less abundance. Acropora palmata, 
a species of another growth habit, is an important reef builder in places. 
It forms ascending fronds which by the thickening of their basal portion 
become very strong. Two species which Hve in the quiet water on the 
flats behind the outer reefs or in the lagoons, are Maeandra areolata, 
which because of its small base of attachment could not remain fixed 
on the reef, and Porites furcata, which because of its fragile branches 
would be smashed to bits by the rough water of the outer reefs. These 
two species can exist where the bottom is muddy, as both possess the 
means necessary for ridding themselves of considerable quantities of 
silt. Eusmilia fastigiata is a species which has a fragile skeleton and 
requires quiet water, but as it can not endure much silt, it is restricted 
to areas where the bottom is cleaner. Porites clavaria illustrates re- 
sponsive adaptation to environment, as it lives both on the reef and on 
the inner flats. The branches of the colonies in the former habitat are 
