_Habia gutturalis_ (Sclater): Red-throated Ant-tanager.--The only breeding records previously available for this species on the peninsula are for May 18 (Paynter, 1955a:280) and June 25 (Paynter, 1955b). Specimens taken between July 14 and August 2 were in full breeding condition. A male (40882) and female (40883) taken 7-1/2 km. W Escárcega were known to be mated. Plumages in all specimens are worn and for that reason specimens were not identified to subspecies. Specimens (6): [Male], 40882, testis 14 × 9 mm., 38.9 gm. (July 14), [Female], 40883, ovary 5 × 5 mm., 29.0 gm. (July 14), and [Male], 40887, testis 10 × 7 mm. (July 16), 7-1/2 km. W Escárcega; [Male], 40885, juv. (rectrices and remiges ensheathed basally) (July 28), and [Female], 40886, ovary moderately active, 30.5 gm., molting--2nd primaries ensheathed (July 28), Pueblo Nuevo X-can; [Male], 40884, testis 15 × 8 mm. (August 2), 4 km. WSW Puerto Juarez. _Saltator atriceps_ (Lesson): Black-headed Saltator.--Previously, breeding has been noted in this species in February, March, and April (Paynter, 1955a:284). A male taken on July 16 was in full breeding condition. Specimens (3): [Male], 40895, testis 15 × 9 mm., 80.4 gm. (July 16), and [Female], 40896, 73.5 gm. (July 17), 7-1/2 km. W Escárcega; [Male], 40894, 71.6 gm. (July 29), Pueblo Nuevo X-can. _Saltator coerulescens_ (Vieillot): Gray Saltator.--The only previous breeding record for this species is for April 26. Our one specimen, No. 40897, a juvenal male barely able to fly, taken on July 21 at Pisté, weighed 43.8 grams. _Richmondena cardinalis_ (Linnaeus): Cardinal.--The only record of breeding previously reported is of a male with enlarged testes taken on June 4 (Paynter, 1955a:287). Adult males with enlarged testes were obtained on July 11 and August 10, and three juveniles were taken southwest of Sisal on August 10, 16, and 18. Specimens (7): [Male], 40903, testis 9 × 7 mm., 39.7 gm. (July 11), and [Female], 40904, 34.0 gm. (July 11), 5 km. S Champotón; [Male], 40898, testis 7 × 4 mm., 33.8 gm. (August 10), and [Female], 40899, juv. (rectrices and remiges ensheathed basally), 32.8 gm. (August 10), 13 km. WSW Sisal; [Male], 40900, fledgling, 18.4 gm. (August 18), 2 km. WSW Sisal; [Female], 40901, ovary granular, 37.4 gm., molting--1st primaries ensheathed (August 15), and [Male], 40902, imm., 34.0 gm. (August 16), 4 km. NNE Felipe Carrillo Puerto. _Cyanocompsa parellina_ (Bonaparte): Blue Bunting.--Specimens (2): [Male], 40906, imm. (July 15), and [Male], 40905, testis 10 × 7 mm., 15.2 mm. (July 15), 7-1/2 km. W Escárcega. _Tiaris olivacea pusilla_ (Swainson): Yellow-faced Grassquit.--The only records of breeding, thus far, are by Paynter (1955a:291) for March 12 and June 14. A male (40907) taken 4 km. NNE Felipe Carrillo Puerto on August 14 had fully enlarged testes (8 × 5 mm.).