branner: the stone reefs of brazil. 257 



" In lithological characters the Abrolhos beds resemble the sandstones, etc., 

 of the Rio Sao Francisco at Penedo, . . . and which contain similar plant 

 remains. They have been disturbed by the same upheaval, and I have little 

 hesitation in referring both to the cretaceous. . . . 



" As we go northward from Cape Frio, the madreporians become quite com- 

 mon on the rocky shores, though the species are not numerous, and they are 

 associated with species of Millepora, ZoantJnis, and Palythoa, and various gor- 

 gonians. I have already called attention to the coral fauna of Guarapary and 

 Victoria, and I have stated that I have no evidence of the existence of any 

 banks of living corals or reefs south of the region of the Abrolhos. Here the 

 conditions for the growth of coral reefs on a large scale are remarkablv favor- 

 able. Over large areas the water covering the great submarine shelf, on which 

 the islands are based, is much under one hundred feet in depth, and it is 

 warm and pure. So it is not to be wondered at that very large coral reefs, 

 both fringing and barrier, are found here. 



" When the tide goes out there is seen extending round about one half the 

 circumference of the island of Santa Barbara a fringing reef. . . . One may 

 then walk out on its level surface as on a wharf, and from its ragged edge 

 look straight down through the limpid green water and see the sides of the 

 reef and the sea bottom covered with huge whitish coral-heads, together with 

 a wealth of curious things not to be obtained without a dredge. 



" The surface of the reef, though flat, is somewhat irregular. It rises but a 

 short distance above low-water mark, and it is overgrown with barnacles, 

 shells, mussels, and serpula-tubes, together with large slimy patches of the 

 common leather-colored Palythoa. The reef abounds in small pools, some 

 shallow and sandy, others deep, rocky and irregular. The former often con- 

 tained scattered masses of corals, particularly Siderastraea and Favia, and they 

 abound in small shells, crabs, Ophiurae, etc. ; but the deep pools are the 

 richest in life. These are usually heavily draped on the sides with brilliantly 

 tinted sea-weeds and corallines, the bare rock being gay with brvozoa and 

 hydroids. The most common coral of these pools is Siderastraea stellata 

 Verrill. . . . 



" The material composing the reef is an exceedingly hard, whitish limestone, 

 ringing under the hammer, and, so far as I had an opportunity to examine it, 

 for the Brazilian reefs are never broken up by the surf, — showing no distinct 

 trace of organic structure. The Santa Barbara reef extends around about one 

 third of the island, and on the northwestern side it reaches across to the 

 ' Cemetery,' so that when the tide is down that islet is joined to the main 

 island by a broad, level platform of rock, diversified by tide-pools, and form- 

 ing an excellent collecting-ground for the naturalist. The reef, built up prin- 

 cipally of Acanthastraea, Siderastraea, etc., has completed its growth on arriving 

 at low-tide level, the upper surface being still farther added to by serpulae, 

 bryozoa, corallines, barnacles, etc., together with the coral-sand and debris of 

 shells accumulating on the reef. 



"So far I have spoken only of fringing reefs, but there are other coral 



VOL. XLIV. 17 



