Dr. P. Wagenaar Hummelinck entrusted me with the study of the snakes, which he collected during his trips to the islands off the north coast of Venezuela, to the Venezuelan mainland, and to eastern Colombia. In the present paper the species collected by Dr. Hummelinck are listed with data on scale counts, coloration and with notes on nomenclature. In a few cases specimens from other collections were used for comparison, and for these the provenance is indicated in the lists of specimens. Dr. Hummelinck made notes on the names given to the different species of snakes by the inhabitants, and by his kind permission these notes are included in the present paper. These local names form an addition to those published by Roca (1932, pp. 387—388). Unless otherwise stated the specimens are in the collections of the Rijksmuseum van Natuurlijke Historie, Leiden. The numbers cited for the different specimens, Oph. 1—60, are the numbers used by the collector; they are mentioned in parentheses, the first of each list of specimens with the indication Oph., the following without this indication.