118 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



historic period it has beeu very shght indeed. The recession of the sea 

 at 4he rate of " ten fathoms in thirty years " as given by Capanema 

 is quite out of the question. 



Changes within Eecent Geologic Periods. 



Views of former loriters. — It is somewhat remarkable that all those 

 who have seen this coast and expressed views about its history have 

 thought it to have been elevated within recent geologic times. These 

 writers are, BanXo de Capanema,^ Liais,^ Hartt,^ and J. Clarke 

 Hawkshaw.'* 



Thomaz Porapeo de Souza Brasil, in his valuable Ensaio Estatistico da 

 provincia do Ceara (p. 49), says that at the Barra do Pacoti in Ceara, "as 

 in Bahia and Rio de Janeiro, proofs are seen of the elevation of the coast," 

 but he does not say what these proofs are. 



It is but fair to these writers that their views and their reasons for 

 holding them should be given. On the other hand, it is but just to 

 recall the fact that a theory becomes really important only when it is 

 supported by adequate evidence. 



1 shall therefore give very briefly what the authors cited regard as 

 evidence of the geologically recent elevation of the coast, and at the same 

 time my own reasons for looking upon the bulk of this evidence as 

 unsatisfactory. 



Hartt presents tangible evidence of elevation along the coast about 

 Rio de Janeiro, and for some distance north of there. This evidence 

 consists of sea-urchin holes, and old water-lines above tide-level on the 

 island of Mavicas, near Rio, on the great conical hill at Victoria, and on 

 the island of Sant' Anna. 



In the article cited Hawkshaw speaks of conclusive signs that the 

 coast has recently, risen" and of " unmistakable signs ... of a recent ele- 

 vation of the coast," but he does not say what these signs are. 



The following are adduced by Liais as facts in support of the elevation 

 theory : — 



1. The schistose structure of the reef rocks. 



^ Trabalhos da Commissao Scientifica de Explora^ao. 1. Introduc^ao, p. 

 cxxi, cxxxvii. Rio de Janeiro, 1865. 



2 E. Liais. Cliraats, geologie, etc. du Bresil, p. 256-261. Paris, 1872. 

 E. Liais. L'Espace Celeste, ed. 2, p. 545-5i8. Paris (1881?). 

 Compt. Rend., 1860, L., p. 762-763. 



3 Geology and physical geography of Brazil, p. 35, 36, 42, 71-72, 344, 



4 Quar. Journ. Geol. Soc, 1879, XXXV., p. 241-243. 



