BIOS SECUKE AND MAMOKE, EASTERN BOLIVIA 23 
river, I travelled as rapidly as possible to Trinidad, descending 
Rio Secure and Rio Mamore. The journey gave me an oppor- 
tunity to map portions of the rivers and provided the data for 
this paper. 
The exigencies of travel made the compilation of the map of 
secondary importance, and therefore the methods used in map- 
