274 bulletin: museum of comparative zoology. 



A species of Agaricia was found growing plentifully in the Mussa 

 clusters. The polyps are of a beautiful brownish-red color with green 

 centres. 



This whole Maceio region is a very interesting one, and deserves more 

 thorough investigation. North of this main reef just described there 

 are many smaller patches of coral rock that may contain some of the 

 other Brazilian corals described from Bahia and the Abrolhos by Verrill 

 and Rathbun. If the collection described in this paper is complete, it is 

 a remarkable fact that the range of a number of the corals so common in 

 the south should end abruptly in the region of Bahia. 



R^suM^ OF Conclusions regarding the Coral Reefs. 



The coral reefs of Brazil extend along the coast from the Abrolhos 

 Islands in south latitude 18° nearly to the mouth of the Amazon River. 

 The reefs, however, are not continuous, but are broken by many and 

 large gaps. The only reefs well off the coast are on tlie Rocas Island in 

 south latitude 3° 51', west longitude 33° 48', and 225 kilometres from 

 the mainland. The reefs of the coast are both barrier and fringing reefs. 

 They are usually narrow, — from ten to fifty metres in width ; the widest 

 are the barrier reefs, some of which are about thirty kilometres in width. 

 Most of the near-shore reefs are quite thin, probably not exceeding a 

 thickness of ten metres ; the reefs that grow further out are thicker, and 

 it is possible that some of the barrier reefs, like those of the Abi'olhos 

 group and of the Cape St. Roque group, have a maximum thickness of a 

 hundred metres at their outer edges. 



There were coral reefs on the Brazilian coast during Cretaceous times 

 and also during Eocene and Pliocene times. The coral reefs may, there- 

 fore, be regarded as having survived since the Pliocene, at least. The 

 reef corals are found both beneath and on top of the stone reefs with 

 which they are contemporaneous. It is highly probable that some of 

 the coral reefs of the coast grow upon and conceal stone reefs. The 

 coral reefs have no connection with eruptive phenomena, with the pos- 

 sible exception of those of the Rocas, which are two hundred and twenty- 

 five kilometres from the mainland. 



Many of the Brazilian coral reefs, having reached the upward limit of 

 growth, are now dead and are growing only laterally. This is true of 

 both the large barrier reefs and of the fringing in-shore reefs. 



The coral polyp fauna of Brazil contains twenty-eight known species. 



