Corals and coral islands.

f

RATE OF GROWTH OF CORALS. 125
years. Again, Major E. B. Hunt mentions, in the American
Journal of Science for 1863, the fact of the growth of a Meandrina at Key West, Florida, to a radius of six inches in twelve
years, showing an average upward increase in this hemispherical
coral of half an inch a year, if, as is evidently implied, this
radius was a vertical radius. Major Hunt deposited specimens of corals of his collection near Fort Taylor, Key West,
in the Yale College Museum, and three of these are labelled
by him as having grown to their present size between the
years 1846 and 1860, or in fourteen years. Two are specimens of OcuUna diffusa; one is a clump four inches high
and eight broad; and the other has about the same height.
The weight of the first of these clumps is forty-four ounces.
The rate of four inches in fourteen years would be equal to
about 3J twelfths of an inch a year in height, or three and oneseventh ounces a year of solid coral. The other specimen is
of the Mceandrina clivosa V.; it has a height of two and a
quarter inches and a breadth of seven and a half inches. This
is equivalent to about a sixth of an inch of upward growth
in fourteen years. The specimen weighs about eighteen ounces.
It is not certain that with either of these specimens the germs
commenced to grow the first year of this interval, and hence
there is much doubt with regard to these calculations.
The following observations are from a paper read by
Prof. Verrill before the Boston Society of Natural History
in 1862. The wreck of a vessel, supposed to have been the
British frigate Severn, lost in 1793 near " Silver Bay," off
Turk's Islands, is covered with growing corals. It lies (according to the journal of Mr. J. A. Whipple, by whom specimens
were collected in 1857) in about four fathoms of water. One
of the specimens was a mass of the species Orbicella annulac
ris, shaped somewhat like a hat; it is attached to the top of as