In the interior of South America, between the second and fourth degrees of north latitude, a forest-covered plain is inclosed by four rivers, the Orinoco, the Atabapo, the Rio Negro, and the Cassiquiare. In this district are found rocks of granite and of syenite, covered with colossal symbolical figures of crocodiles and tigers, and drawings of household utensils, and of the sun and moon. The tribes nearest to its boundaries are wandering naked savages, in the lowest stages of human existence, and far removed from any thoughts of carving hieroglyphics on rocks. One may trace in South America an entire zone, extending through more than 8° of longitude, of rocks so ornamented, viz, from the Rupuniri, Essequibo, and the mountains of Pacaraima, to the banks of the Orinoco and of the Yupura. These carvings may belong to very different epochs, for Sir Robert Schomburgk even found on the Rio Negro representations of a Spanish galiot, which must have been of a later date than the beginning of the sixteenth century; and this in a wilderness where the natives were probably as rude then as at the present time. Some miles from Encaramada there rises in the middle of the savannah the rock Tepu-Mereme, or painted rock. It shows several figures of animals and symbolical outlines which resemble much those observed by us at some distance above Encaramada, near Caycara. Rocks thus marked are found between the Cassiquiare and the Atabapo and, what is particularly remarkable, 560 geographical miles farther to the east, in the solitudes of Parime. Nicholas Hortsmann found on the banks of the Rupunuri, at the spot where the river winding between the Macarana mountains forms several small cascades, and before arriving at the district immediately surrounding lake Amucu, “rocks covered with figures,” or, as he says in Portuguese, “de varias letras.” We were shown at the rock of Culimacari, on the banks of the Cassiquiare, signs which were called characters, arranged in lines, but they were only ill-shaped figures of heavenly bodies, boa-serpents, and the utensils employed in preparing manioc meal. I have never found among these painted rocks (piedras pintadas) any symmetrical arrangement or any regular even-spaced characters. I am therefore disposed to think that the word “letras,” in Hortsmann’s journal, must not be taken in the strictest sense.