is a tributary to the Amazon River
west of the Nanay
, and is navigable for 125 miles from its confluence with the Amazon. Like the Nanay, it flows entirely on the plains. Its mouth is 42 miles west of the junction of the Ucayali
with the Amazon. Continuing west from the Tigre we have the Parinari, Chambira, and Nucuray, all short lowland streams, resembling the Nanay in character.