ZOOLOGY; L. R. GARY 
285 
Though it can be shown that the 962 cases of chorea originated from 
6 or 7 ancestors and that the tendency has been handed down ahnost 
without a break through the generations and that for generations there 
have been individuals who recognized the hereditary nature of the dis- 
ease and were influenced in marriage accordingly; nevertheless, there is 
no clear evidence that persons belonging to the choreic lines voluntarily 
abstain to any marked degree from, or are selected against, in marriage. 
THE ALCYONARIA AS A FACTOR IN REEF LIMESTONE 
FORMATION 
By L. R. Gary 
DEPARTMENT OF BIOLOGY. PRINCETON UNIVERSITY 
Presented to the Academy, March 24, 1915 
The early students of coral reef formation based their conclusions 
concerning the depth at which reef formation could take place and the 
rate at which material was added to such reefs upon the known bathy- 
metrical distribution and growth rate of stony corals (Madreporaria). 
The results obtained from the examination of the cores from borings 
made at the Island of Funafuti in the South Pacific showed that, in 
this particular region at least, calcareous algae of the genus Halinieda 
were a very important factor in reef limestone formation. Among the 
other group of lime secreting animals, those species of Alcyonaria, which 
form a massive skeleton have received proper recognition as contribu- 
ting to reef formation. The remaining representatives of this group have 
been neglected as reef formers because their limy secretion is laid down 
in the form of minute spicules which are set free at the time of the dis- 
integration of the living tissues of the colony leaving no recognizable 
skeleton. 
On most coral reefs in all parts of the world the Alcyonaria with free 
spicules are much more abundant than those forming a massive skeleton 
while in many regions they constitute by far the greatest part of all 
lime secreting organisms living permanently attached to the bottom. 
On many reef areas in the Florida- An tillean region the areas occupied by 
stony corals and calcareous algae are relatively small while flexible al- 
cyonaria or the family Gorgonaceae make up the most characteristic 
feature of the fauna. The spicules of these organisms are found in 
practically all bottom samples both from the crests of the reefs and in 
the soft mud from the channels between the reefs so it is evident that 
they may be incorporated into the reef limestones before they have 
undergone marked erosion. 
