i68 



THE LOWER AMAZONS 



of crocuses. These Callidryades seem to be migratory- 

 insects, and have large powers of dissemination. During 

 the last two days of our voyage the great numbers con- 

 stantly passing over the river attracted the attention of 

 every one on board. They all crossed in one direction, 

 namely, from north to south, and the processions were 

 uninterrupted from an early hour in the morning until 

 sunset. All the individuals which resort to the margins 

 of sandy beaches are of the male sex. The females are 

 much more rare, and are seen only on the borders of 

 the forest, wandering from tree to tree, and depositing 

 their eggs on low mimosas which grow in the shade. The 

 migrating hordes, as far as I could ascertain, are com- 

 posed only of males, and on this account I believe their 

 wanderings do not extend very far. In confirmation of 

 this is the fact that, although the same species generally 

 has a very wide range, some being found from the central 

 parts of the United States down to 32° S. lat., yet each 

 distant region has its tolerably distinct local variety. 

 But the effect of this general wandering habit of the group 

 is, in the long run, a wide dissemination of the species ; 

 the formation of local varieties showing that the process 

 is, nevertheless, a slow one. None of the species are 

 found much beyond the tropics, but the genus is well 

 represented within the tropical zone throughout the world ; 

 and an East Indian kind (C. Alcmeone) is so nearly allied 

 to a South American one (C. Statira), as to have been 

 mistaken for it by some authors. 



A strange kind of wood-cricket is found in this neigh- 

 bourhood. The males produce a very loud and not un- 

 musical noise by rubbing together the overlapping edges 

 of their wing-cases. The notes are certainly the loudest 

 and most extraordinary that I ever heard produced by 

 an orthopterous insect. The natives call it the Tanana, 

 in allusion to its music, which is a sharp, resonant stridu- 

 lation resembling the syllables ta-na-na, ta-na-na, suc- 

 ceeding each other with little intermission. It seems to 

 be rare in the neighbourhood. When the natives capture 

 one they keep it in a wicker-work cage for the sake of 

 hearing it sing. A friend of mine kept one six days. It 

 was lively only for two or three, and then its loud note 

 could be heard from one end of the village to the other. 

 When it died he gave me the specimen, the only one I was 

 able to procure. It is a member of the family Locustidae, 



