ZOOPHYTES. 
487' 
to fifteen fathoms, the same length in ten years ; at 
the depth of one hundred fathoms, the same length 
in twenty-five or thirty years ; and, at the depth 
of one hundred and fifty fathoms, the same length 
in forty years. It is also remarked, that in gene- 
ral the colour of the coral is deeper and richer in 
shallow than in very deep water. The coral of 
Barbary is not reckoned so fine as that of Italy 
or of France. 
Many species of madrepores are found on the 
African coasts, from N. L. 30° to S. L. SO" ; but 
it is not true, as some maintain, that the same 
species are distributed throughout the whole 
range of latitude just mentioned ; on the contra- 
ry, each species has its determinate place of 
abode, and of geographical distribution. The 
number of species increase as we advance towards 
the warmer regions ; but to the north and the 
south of the latitudes just mentioned they occur 
very rarely, and in but small quantity. 
Gorgonias, or sea-fans, millepores, corallines, 
sertularias, cellularias, alcyoniums, and sponges, 
are, in general, found most abundantly in the wa- 
ters of the ocean, in latitudes to the north and 
south of the continent of Africa. Yet, on the 
coast of Africa, as at Tunis, also in the Red Sea, 
the common officinal sponge {spongia officinalis^ 
Lin.) is fished up in considerable quantity, and 
forms a regular article of trade. 
