This field book consists of the field notes of William R. Maxon, from field work in Costa Rica in 1906. Collector numbers 1 through 717 are included. Entries include: collector number, scientific name or common name, locality, and date. Localities include: San Jose, Cartago, Turrialba, Caliblanco, Pacayas, La Palma, Santa Domingo de Mateo, Finca Novarro, and possibly others. Some rough sketches of specimens are included.