The Web of the Golden Spider (1909) by Frederick O. Bartlett is a Lost Race tale set in the Andes, where treasure and its guardians are soon discovered. 

The Web of the Golden Spider is a tale of mystery, intrigue and adventure that begins in the city, progresses to a mutinous open sea voyage, eventually leading to the remotest areas on the slopes of the Andes of South America.

Wilson, our hero, finds himself in the midst of a battle between a deposed queen and revolutionists who have banded together in an effort to bring their country together as a republic. Wilson, although torn between helping mercenaries, freedom fighters and revolutionaries, is more concerned with the rescuing of the girl he has fallen in love with, but who has been snatched from him by a mysterious priest. That, and the finding of the famed treasure of El Dorado rumored to have been buried beneath Lake Guadiva.

Frederick Orin Bartlett (1876-1945) was a US author of several adventure novels.