542 Brazilian Corals and Coral Reefs. (September, 
masses, conforming more or less in size and shape to the projec- 
tions from which they spring. This law of variation seems to 
hold good for the entire coast. A small species of Porites occurs 
at times, associated with the two species above named. 
A little deeper down, where they can seldom, if ever, be uncov- 
ered by even the lowest tides, come in other and more showy 
corals. Mussas grow profusely at many localities, seeming to 
prefer the abrupt outer edges of the submerged rocks. They 
belong to two species, one with separated cells not now living in 
the Bay of Bahia, the other having the cells closely joined nearly 
to their summits. Occasionally we find small heads of Orbicella 
and Acanthastrza in similar situations, but these more commonly 
inhabit deeper water. The same may also be said of Millepora, 
the hydroid coral, of which there are two common and one rare 
species on the Brazilian coast ; in very shallow water it is stunted 
in growth and usually bears only short branches. Living on the 
under sides of stones, in company with encrusting bryozoans, is 
a very small Astrangian, consisting of many widely separated 
cells united by thin creeping stolons. 
An Agaricia, very rare in the Bay of Bahia but more common 
elsewhere, generally grows attached to some other coral, as, for 
instance, to the dead base of Mussa. On the coast of Pernam- 
buco there is also a small Stylaster attaching itself in the same 
way. Pectinia braziliensis is seldom found adhering to a rocky 
surface, but is very abundant at times in sheltered situations, 
partly buried in the mud. There remains only a single other 
Madreporian coral to mention here; it is the Porites solida, which 
‘seems to live nearly everywhere excepting in the Bay of Bahia. 
This closes the list, with one or two exceptions of rare species, 
of the shallow water Madreporian corals of Brazil. The most of 
the species enumerated are very widely distributed, ranging along 
the entire coast north of Cape Frio. But they are not confined 
to the shore, for the majority also occur on the outer reefs, which 
are, so far as we know, entirely built up of a few of these same 
species. From depths ranging from twenty-seven to forty fath- 
oms were procured several small corals; but these forms can, at 
‘the most, play only a very insignificant part in reef-building. 
Let us return, however, to our studies in the bay. Five or six 
‘species of Gorgonians are abundant nearly everywhere, growing _ 
~ as commonly from small stones and dead corals imbedded in the 
