Specimens (2): [Male], 40411, testis 5 mm., 207.3 gm. (August 10), 4 km. N San Miguel; [Female], 40412, 242 gm. (August 10), 3-1/2 km. N San Miguel. _Buteo magnirostris conspectus_ (Peters): Roadside Hawk.--This species was the commonest hawk on the peninsula and was seen at all localities except Isla Mujeres and Sisal. Specimens (5): [Male], 40409 (July 12), and [Female], 40410, ova to 1 mm., 249 gm. (July 16), 7-1/2 km. W Escárcega; [Male], 40413, 279 gm. (July 17) 1 km. N, 13 km. W Escárcega; [Male], 40407, testis 5 × 2 mm., 254.7 gm. (July 23), Pisté: [Female], 40408, ovary inactive, 279.0 gm. (July 28), Pueblo Nuevo X-can. _Buteo brachyurus_ Vieillot: Short-tailed Hawk.--Our one specimen, a male (40414) weighing 342 gm. and in white-bellied phase, was taken by a native 6 km. W Escárcega on July 14. The testes were inactive. _Buteo nitidus plagiatus_ (Schlegel): Gray Hawk.--Our specimen is one of two subadults sighted near a large milpas, on Rancho San Miguel. Specimen (1): [Male], 40415, testis 5 × 3 mm., 364 gm. (August 15), 4 km. NNE Felipe Carillo Puerto. Mallophaga: _Craspedorrhy_ sp. _Buteogallus anthracinus_ (Lichtenstein): Common Black Hawk.--Five individuals were seen on August 23 along a stretch of five miles of highway about 30 mi. SW Champotón, Campeche. The species was identified from the description given in Blake (1953). The hawks were perched on dead limbs in full view, 50 to 100 feet from the highway, which at this locality parallels the beach, sometimes only a few yards from the water. _Ortalis vetula intermedia_ Peters: Chachalaca.--Chachalacas were heard or seen at all localities on the mainland except Sisal. Specimens (3): [Female], 40416, 423 gm. (July 13), [Female], 40417, 432 gm. (July 15), and [Female], 40418, ovary 12 × 9 mm., 408.5 gm. (July 16), 7-1/2 km. W Escárcega. Mallophaga: _Amyrisidea spicula_, July 16. _Colinus nigrogularis persiccus_ Van Tyne and Trautman: Black-throated Quail.--These quail were abundant in the arid scrub west of Sisal. Several coveys of half-grown chicks were seen and specimens taken were in full breeding condition. On a two-mile walk on August 18, in the coastal scrub about 5 km. W Sisal, a pair of quail was seen about every 100 paces. Specimens (4): [Female], 40422, ovum in oviduct 30 x 22 mm., 147.5 gm. (August 10), [Female], 40420, ovum in oviduct 27 mm., 151.7 gm. (August 18), [Male], 40421, testis 9 × 5 mm., 119.6 gm. (August 18), and [Male], 40419, testis 11 × 6 mm., 145.7 gm. (August 18), all from southwest of Sisal. _Laterallus ruber_ (Sclater and Salvin): Little Red Rail.--Two specimens were taken about 3-1/2 km. N San Miguel, Isla Cozumel, in tall grass. One bird was shot when flushed; the other was caught in a Museum Special mousetrap. I follow Brodkorb (1943) and Paynter (1955a) who did not recognize subspecies in this species.