FORMATION OF CORAL REEFS AND ISLANDS. 247 
extension of the reef off Point Venus, the east cape. There 
is no stream on the coast opposite this interruption in the 
reef, except toward Point Venus; and at the present time 
the waters find their principal exit east of the Point, behind 
a large coral reef, a quarter of a mile distant. 
_ Scale of 500 meters 
100__200___300__400. “B00. iia 
10) & 
43° «12 
Dolphin Shoal 

PART OF NORTH SHORE OF TAHITI. 
It is evident that the growth of coral reefs is not much 
retarded about Tahiti by fresh-water streams. In fact none 
of these so-called rivers are over three feet in depth; and the 
most they can do is to produce a thin layer of brackish water 
over the sea within the channels. 
