XXXV 



there was noticed " an intricate wilderness of lakes, in some of 

 which were fresh, in others salt-water shells. Of the former 

 kind I found a lAmncm in great nmnbers in a lake, into which 

 the inhabitants assured me that the sea enters once a year, and 

 sometimes oftener, and makes the water quite salt. I have no 

 doubt many interesting facts, in relation to marine and fresh- 

 water animals, might be observed in this chain of lagoons, which 

 skirt the coast of Brazil. M. Gay has stated that he found, in 

 the neighbourhood of Rio, shells of the marine genera Solen arid 

 Mytilus and fresh-water Ampidlariee living together in brackish 

 water. I also frequently observed, in the lagoon near the Botanic 

 Garden, where the water is only a little less salt than in the sea, 

 a species of HiidropMlus, very similar to a water-beetle common 

 in the ditches of England ; in the same lake the only • shell 

 belonged to a genus generally found in ebtuaries." 



AVhilst staying at Rio, Mr. Darwin resided in a cottage at 

 Botofogo Bay, close beneath the well-known mountain of the 

 Corcovado. Here, "the climate during the months of May and 

 June [1832] , or at the beginning of winter, was delightful. The 

 mean temperature .... was only 72°. It often rained heavily, 

 but the drying southerly winds soon again rendered the walks 



pleasant After the hotter days it was delicious to sit 



quietly in the garden and watch the evening pass into night. 

 Nature, in these climes, chooses her vocalists from more humble 

 performers than in Europe. A small frog, of the genus Hyla, 

 sits on a blade of grass about an inch above the • surface of the 

 water, and sends forth a pleasing chirp ; when several are 

 together they sing in harmony on different notes. . . . Various 

 Cicada and crickets at the same time keep up a ceaseless shrill 

 cry, but which, softened by the distance, is not unpleasant. 

 Every evening after dark this great concert commenced, and 

 often have I sat listening to it, until my attention has been 

 drawn away by some curious passing insect. 



" At these times the fire-flies are seen flitting about from 

 hedge to hedge. On a dark night the light can be seen at about 

 two hundred paces distant. It is remarkable that in all the 

 different kinds of glow-worms, shining Elaters, and various 

 marine animals (such as the Crustacea, Meduscs, Nereidce, a 

 coralline of the genus Clijtia, and Pijrosoma) which I have 



