16), and ♂, 40503, testis 5 × 3 mm., 320.5 gm. (August 16) 4 km. NNE Felipe Carrillo Puerto.

Chordeiles acutipennis micromeris Oberholser: Trilling Nighthawk.—This species was common in the arid coastal scrub west of Sisal, where hundreds could be seen flying every evening. They were common also at Puerto Juarez, but uncommon at Felipe Carrillo Puerto.

Specimens (2): ♂, 40506, testis 5 × 3 mm., 57.3 gm. (August 1), 5 km. WSW Puerto Juarez; ♀, 40507, ovary 4 × 3 mm. (inactive), 37.0 gm. (August 16), km. NNE Felipe Carrillo Puerto.

Nyctidromus albicollis yucatanensis Nelson: Parauque.—This species was especially common in the vicinity of Felipe Carrillo Puerto and on Isla Cozumel, and was seen at every collecting locality. A flightless, juvenal female was obtained by local boys at Pisté on July 21. Therefore the reproduction period seems to be longer than Paynter's (1955a:141) data suggested.

Specimens (5): ♂, 40512, testis 7 × 3 mm., 75 gm. (July 10), 5 km. S Champotón; ♀, 40508, juv. (remiges and rectrices ensheathed basally), 44.2 gm. (July 21), Pisté; sex? 40510, 55.5 gm. (August 8), and ♂, 40509, testis 3 × 1 mm., 73.5 gm., molting—outermost two pairs of primaries ensheathed (August 10); 3½ km. N San Miguel, Isla Cozumel; ♂, 40511, 72.9 gm. (August 15), 4 km. NNE Felipe Carrillo Puerto.

Caprimulgus salvini badius (Bangs and Peck): Salvin's Whip-poor-will.—My only record of this species is provided by a female (40513) taken 3½ km. N San Miguel, Isla Cozumel, on August 8. The specimen weighed 58 grams, had an inactive ovary (6 × 4 mm.), and was molting (8th and 9th primaries ensheathed).

Chateura vauxi gaumeri Lawrence: Vaux Swift.—This species was seen at almost every locality visited. The only specimens obtained were brought in by a boy at Pueblo Nuevo X-can on July 30; he said he captured them in his house. Two of them were adults and four were fully-feathered young-of-the-year.

Specimens (6): ♂, 40516, testis 4 × 2 mm., ♀, 40519, ovary inactive, ♂, 40514, juv., 12.6 gm., ♂, 40515, juv., ♀, 40517, juv., and ♀, 40518, juv. (July 30) Pueblo Nuevo X-can.

Campylopterus curvipennis pampa (Lesson): Saber-wing.—A female (40522), shot 7½, km. W Escárcega on July 16, seems to provide the first record of breeding (ovum 6 mm. in oviduct) by this species on the peninsula. A non-breeding female (40521) that weighed 5.0 gms. was taken 4 km. NNE Felipe Carrillo Puerto on August 14.

Chlorostilbon canivetii canivetii (Lesson): Canivet Emerald.—This bird was seen at all localities at which we collected on the mainland.

Specimens (4): ♀, 40530, ovary moderately active, 3.0 gm. (July 22), ♂, 40525, 2.1 gm. (July 23), and sex? 40526, 2.9 gm. (July 25), Pisté; ♀, 40529, ovary inactive, 2.4 gm. (July 26), 3½ km. N Pisté.

Chlorostilbon canivetii forificatus Ridgway: Canivet Emerald.—The specimen is slightly larger than those taken on the mainland and is clearly referable to C. c. forificatus, a subspecies endemic to Isla Cozumel.

Specimen (1): ♀, 40534, ovary inactive, 2.8 gm. (August 8), 3½ km. N San Miguel, Isla Cozumel.

Amazilia candida candida (Bourcier and Mulsant): White-bellied Emerald.—This species seemed to be the commonest hummingbird at most localities on the mainland. However, it was not seen along the coasts.

Specimens (5): ♂, 40535, testis 3 mm., 2.9 gm. (July 12), and ♂, 40536, testis 2 mm., 3.6 gm. (July 14), 7½ km. W Escárcega; ♂, 40531, testis 2 mm., 4.3 gm. (July 28), ♂, 40532, 3.8 gm. (July 28), and ♀, 40533, ovary inactive, 3.9 gm. (July 29), Pueblo Nuevo X-can.

Amazilia rutila (DeLattre): Cinnamomeous Hummingbird.—In addition to the two localities from which specimens were taken, several individuals were seen near the airstrip at Puerto Juarez.

Specimens (2): ♀, 40538, ovary inactive, 4.1 gm. (July 30), 1½ km. S, 1 km. E Pueblo Nuevo X-can; ♂, 40539, testis 2 mm. (August 14), 4 km. NNE Felipe Carrillo Puerto.

Amazilia yucatanensis (Cabot): Yucatán Hummingbird.—Many of these hummingbirds were seen among the coco palms on Isla del Carmen. A female taken on August 14 with a moderately enlarged ovary may indicate that the breeding season extends well into the summer.

Specimens (4): ♂, 40540, testis 2 mm., 4.7 gm. (July 7), ♀, 40541, ovary inactive, 3.0 gm. (July 8), and ♂, 40543, 3.0 gm. (July 8); 1 km. SW Puerto Real, Isla del Carmen; ♀, 40542, ovary 6 × 2 mm. (ova to 1 mm.), 2.9 gm. (August 14), 4 km. NNE Felipe Carrillo Puerto.

Trogon citreolus melanocephala Gould: Citreoline Trogon.—This species was heard or seen at all localities where deciduous forest was present.

Specimens (7): ♀, 40557, ovary 14 × 8 mm. (ova to 2 mm.), brood patch, 72.5 gm. (July 16), and ♂, 40558, 66.5 gm. (July 16), 7½ km. W Escárcega; ♂, 40553, 74.0 gm. (August 1), ♀, 40552, 74 gm. (August 1), ♀, 40554, ova to 3 mm. (August 2), and ♂, 40555, 76.2 gm. (August 2), 4 km. WSW Puerto Juarez; ♀, 40556, 76.4 gm. (August 15), 4 km. NNE Felipe Carrillo Puerto.

Chloroceryle americana septentrionalis (Sharpe): Green Kingfisher.—My only specimen is a male (40559) shot near a large aguada at Rancho San Miguel, 4 km. NNE Felipe Carrillo Puerto on August 16. The specimen weighed 40.5 gm.

Ceryle torquata (Linnaeus): Ringed Kingfisher.—Paynter (1955a:154) noted that this "species has not been recorded from Yucatán but it is undoubtedly present, at least in the sheltered lagoon behind the barrier bar." A single individual was seen in one of these lagoons on August 9 and 10.

Eumomota superciliosa superciliosa (Sandbach): Turquoise-browed Motmot.—On July 9 this species was nesting in a large "colony" 5 km. S Champotón, Campéche, in a large abandoned gravel pit having vertical banks about 10 feet high. The pit was an irregular semicircle with an approximate radius of 100 yards and was bordered by a road on one side and elsewhere by low scrub vegetation. The pit was one of several found in the area and formerly was used as a source of limestone gravel used in constructing the road between Champotón and Escárcega. The exposed limestone substratum was overlaid with chalky soil six to eight feet deep.

Motmots were nesting in burrows dug in the layer of surface soil. A total of 101 burrows seemed to be in use or to have been used in 1962. Nine appeared to be unused and 24 burrows evidently were abandoned before they were finished. The depths of 12 burrows selected at random were 34, 32, 37, 25, 28, 44, 36, 36, 24, 37, 22, and 43 inches, and averaged 33.4 inches. In cross-section the burrows varied from round (three inches in diameter) to oval (three inches high and four inches wide). The inner ends of the burrows were enlarged with a depression in the floor, where the eggs were laid.

The long axes of most burrows were straight and perpendicular to the face of the bank in which they were dug; two burrows nevertheless were curved laterally, and one was U-shaped, having two entrances that opened about 12 inches apart.

Eggs and nestlings were found lying on the bare soil at the inner ends of the burrows; no nesting material was found.

The contents of 10 burrows that were excavated are summarized in Table 1. Three nests contained no eggs or young. One of these was freshly dug. The other two empty burrows apparently had been recently occupied by nestlings and contained the foul smelling remains of fecal material, hundreds of beetle wings, and other undigestible parts of insects. The manure was teeming with large fly larvae.

Table 1. Contents of