_Cochlearius cochlearius_ (Linnaeus): Boat-billed Heron.--Three individuals were seen on a small point of land immediately south of the village on the west coast of Isla Mujeres on the afternoon of August 1. One was foraging in a small cove about one mile south of the village on the morning of August 2. Paynter (1955a) did not list the species for Isla Mujeres; our observations seem to constitute the first records for the island. _Mycteria americana_ Linnaeus: Wood Ibis.--A flock of about 15 flew over our camp 4 km. NNE Felipe Carrillo Puerto on August 14. _Sarcoramphus papa_ (Linnaeus): King Vulture.--Our specimen was one of two individuals seen at a cenote. Specimen (1): [Male] 40403, testes inactive, 8 lbs. (July 29), 1 km. N Pueblo Nuévo X-can. Mallophaga: _Colpocephalum megalops_. _Carthartes burrovianus_ Cassin: Yellow-headed Vulture.--We saw several Yellow-headed Vultures on Isla del Carmen on July 6, 7, 8, and 9. _C. burrovianus_ was more abundant than either _Carthartes aura_ or _Coragyps atratus_ in the vicinity of Champotón, where we confirmed field identifications by taking a specimen. Until Wetmore (1950) clarified the status of _C. burrovianus_ in southern Mexico and Central America, the species had gone unnoticed or misidentified as _C. aura_. The Mexican Checklist (Friedmann, Griscom, and Moore, 1950) omitted _C. burrovianus_ from the avifauna of México. Blake (1953) included Tabasco, Chiapas, and Veracruz within the range of the species, but Paynter (1955a) omitted it from his list of birds of the Yucatán Peninsula. Our specimen seemingly constitutes the first record from the peninsula. Specimen (1): [Male], 40404, testes inactive, 1-3/4 lb. (July 9), 2 km. S Champotón. _Chondrohierax uncinatus uncinatus_ (Temminck): Hook-billed Kite.--A pair was seen 5 km. S Champotón on July 8 and 9. Both birds were in adult plumage and appeared to be mated, although we found no nest. The male is referable to _C. u. uncinatus_ on the basis of the narrow white ventral bands, most of which are 0.3 millimeter or less in width. None of the bars exceeds 0.5 millimeter in width. Paynter (1955a) discussed in detail the contradictions in the literature concerning the geographic range of this subspecies, and referred a male in his collection taken in February, 1952, to _C. u. aliquonis_. Traylor (1941) collected a large series of this species in Yucatán and Campeche in winter and allocated the specimens to the nominate form. At Pisté, on July 23, a nestling approximately half-grown was brought in by a local boy. The rectrices were partly ensheathed and the feather count extensively downy. Specimens (2): [Male], 40406, testis 9 × 5 mm., 215.0 gm. (July 10), 5 km. S Champotón; [Male], 40405, nestling, 117.6 gm. (July 24), Pisté. _Buteo magnirostris gracilis_ (Ridgway): Roadside Hawk.--This was the only hawk seen on Isla Cozumel.