Pisté.--Lat. 20° 42´ N, long. 88° 28´ W, elevation 10 meters. A village in dense, low deciduous forest with many nearby _milpas_. Collections were made in a wide area in the vicinity of the village, including nearby Chichén-Itzá. Sisal.--Lat. 21° 10´ N, long. 90° 00´ W, sea level. A small village on the north-western coast of the peninsula. Collections were made on the beach, in the low scrub vegetation behind the beach, and in the mangrove swamps and nearly-dry lagoons further inland, from three to 13 kilometers west-southwest of the village. ANNOTATED LIST OF SPECIES Catalogue numbers in the following accounts are those of the Museum of Natural History, The University of Kansas. With the exception of a synoptic collection presented to the Departamento de la Fauna Silvestre, Dirección General de Caza, México, D.F., all of the specimens mentioned are in the museum at the University of Kansas. Unless otherwise indicated, specimens taken were not molting. For birds undergoing postnuptial or postjuvenal molt, the degree of advancement of the molt is indicated by the numbers of primaries and rectrices that are new or partly ensheathed. Information on the condition of the testes refers to the left testis unless otherwise noted. Scientific and vernacular names follow Friedmann _et al._ (1950) and Miller _et al._ (1957) except for specimens of species or genera that have been more thoroughly treated systematically since the publication of the Mexican Checklist, for example, _Columbina_, _Centurus_ and _Platypsaris_, by Johnston (1962), Selander and Giller (1963), and Webster (1963), respectively. The trinomial is used whenever subspecific identities could be made with a reasonable degree of certainty. The specimens of several kinds were in extremely worn plumage or in molt and meaningful judgments concerning such characters as relative darkness or paleness of plumages could not be made. Specimens are listed in each account according to the temporal order in which they were collected. _Bulbulcus ibis_ Linnaeus: Cattle Egret.--Our specimen is one of three individuals seen feeding near cattle at Rancho San Miguel on August 13 and 14. Specimen (1): [Male], 40401, testis 6 x 2 mm., 289.5 gm. (August 14), 4 km. NNE Felipe Carrillo Puerto. _Casmerodius albus_ (Linnaeus): American Egret.--We took one egret from a flock of about 20 that flew low over our campsite on the morning of July 12. Specimen (1): [Female], 40402, ovary inactive, 10 x 5 mm., 607.5 gm. (July 12), 5 km. S Champotón. Mallophaga: _Ciconiphilus obscurus._