4 MARINE BIOLOGY OF THE SUDANESE RED SEA. 
On the Etuleh and Kal el Kebira shoals abound corals of reef-forming 
species with the Aleyonarians so characteristic of the tropics. Their luxuri- 
ance is perhaps not quite that attained further south, but is amply sufficient to 
constitute a typical specimen of tropical life. This is at 29° 58’ N. latitude ; 
whereas on the other side of Africa corals are scanty, and most forms of life 
are those characteristic of the Mediterranean, as far south as the Cape Verde 
Islands in lat. 15° N.* 
Suez is indeed the place for a tropical laboratory ; less than a week 
from London, most species of the tropics can be studied without any of the 
discomforts of heat. Indeed I can testify that Suez has the best climate to 
be found in Lower Egypt, Alexandria not excepted. 
2. Rep Sea, West Coast Harsours. 
During my voyage south, which I made in a small vessel, I was able to. 
see many little-known harbours and reefs of the Western Shores. The 
uniformity of the biological conditions of the Red Sea was the most striking 
impression received, and subsequent more detailed explorations have done 
little to modify this. 
Of all seas this deserves best the name of The Coral Sea. Its shores are 
all composed of elevated coral, and are fringed with its luxuriant growth ; 
while Barrier and other reefs and patches fill the sea for miles from either 
shore. In short, corals luxuriate everywhere (with one partial exception 
noted below) except in the most stagnant creeks. 
For a detailed description of this coast I refer to the paper following. 
The presence of very numerous inlets into the coral plain is a specially 
important feature from the collector’s point of view. These are, however, all 
of the same type—an opening in the fringing reef bounded by precipitous 
banks of coral, which extend as submarine walls along each side of the canal- 
like creek. The species of coral change as one goes up the creek and several 
kinds of Alcyonaria become prominent, great sheets of brown Xenia being 
especially characteristic of sheltered and cloudy water. 
Only close to the head of the tideless landlocked canals do corals disappear 
and give place to bare mud or sand, with Zostera and Halimeda as the usual 
seaweeds of this habitat. 
So if we reckoned all coral-reefs alike, we have conditions of extreme 
simplicity—land and sea both being coral and the products of its decay. 
But besides the infinite complexity of each coral-reef considered by itself, 
it must be remembered that the reef of the open sea is quite another thing 
to the product of perhaps equally luxuriant growth in sheltered water. 
* Crossland, C. ‘The Gicology and Deposits of the Cape Verde Islands,” P. Z.S. 1905, 
pp. 170-186. 
