The localities for each of the specimens examined are given in the following paragraphs. The arrangement of the data is as follows: alphabetically by country, state (department or province), and locality; alphabetically by the first letter in the abbreviations for the museums, and numerically after each museum abbreviation. Specimens lacking precise locality data are listed first in the most restricted political unit possible; localities which have not been found on maps or the positions of which are not known to us are given in quotation marks. Where more than one specimen is included under one museum number, the number of specimens is given in parentheses after the museum number. Unless noted otherwise, all specimens are alcoholics. _Osteocephalus buckleyi_ BOLIVIA: _El Beni_: Ivon, BMNH 1967.2070-1. _Santa Cruz_: Buenavista, CM 4333, 4339, UMMZ 66563-5. BRASIL: _Amapa_: No specific locality, WCAB 13284. COLOMBIA: _Amazonas_: Rio Guacaya, USNM 152759. _Huila_: Acevedo, Rio Suaza, FMNH 69702. _Narino_: Rumiyacu, FMNH 54756. _Meta_: Rio Guejar, Campamento La Macarena, USNM 152199. ECUADOR: No specific locality, NHMW 6209, WCAB 35499. _Chimborazo_: Pallatanga, BMNH 1947.2.13.46; Santiago, FMNH 42529. _Morona-Santiago_: "Rio Santiago" (= Rio Zamora), MIZS 2950. _Napo_: Lago Agrio, KU 126646; Puerto Libre, Rio Aguarico, KU 123172; Santa Cecilia, AUM 8138, KU 105208-9, 109506, 123171. _Pastaza_: Alpayacu, BMNH 1912.11.1.64; Canelos, BMNH 1947.2.13.40-1, 1947.2.13.43-5; Colonia Mena, Rio Conambo, ZSM 33/1962; Don Tomas, USNM 166014; Guache, Rio Pastaza, AMNH 79986; Rio Bobonaza, USNM 166005; Rio Capahuari, USNM 166554; Rio Conambo at Rio Shiona-yacu, USNM 166018; Rio Copataza, upper Rio Pastaza, USNM 166007-13; Rio Pastaza, NHRM 1946; Rio Pucyacu, USNM 165997 (skeleton), 165998-6001; Rio Rutuno, USNM 166006; Rio Villano, USNM 166002-4; Sarayacu, BMNH 1947.2.13.36-9, MCZ 26090, ZMB 10166. GUYANA: _Mazaruni-Potaro_: Kartabo, AMNH 70971; Membaru River, upper Mazaruni River, UMMZ 85168; Oko Mountains, FMNH 26722-3. _North West_: Amakura River, Haulover, UMMZ 83558-9. _Rupununi_: Marudi River, AMNH 46233; Shudi-kar-wau, AMNH 49252. _West Demerara_: Dunoon, UMMZ 52449, 52508. PERU: _Junin_: Chanchamayo, BMNH 1911.12.13.79-80. _Loreto_: Andoas, AMNH 79984-5; Cashiboya, AMNH 43454; San Antonio, Rio Itaya, AMNH 43218. _Puno_: Yahuaramayo, BMNH 1913.2.25.7. SURINAM: _Suriname_: Powakka, CM 44217. SOUTH AMERICA: No specific locality, NHMW 6208. _Osteocephalus leprieurii_ BRASIL: _Acre_: Tarauaca, FMNH 83247. _Amazonas_: Rio Javari, Benjamin Constant, CAS-SU 12620; Rio Uaupes, north of Rio Japu, NHMG 489. COLOMBIA: _Amazonas_: Gino-goje, lower Rio Apoporis, MCZ 28038, 28040-2, 28044, USNM 152136-8.