Third primary, very little longer than second, and second than first. First rather longer than fourth. Extremities of wings reaching within an inch and a quarter of end of tail. End of tail more rounded than in last species. In. Total length 7½ Wings 5 Tail 4 Tarsi ⅝ Middle toe, from tip of claw to joint of foot ⁹⁄₁₂ From tip of beak to rictus 1 Habitat, La Plata, (_September_). This species is not uncommon on the wooded banks of the Parana, near Santa Fé. If disturbed, it rises from the ground, in the same inactive manner as the European species. I saw one alight on a rope diagonally, but not so completely in a longitudinal position as does the _C. Europæus_, nor transversely as other birds. Mr. Gould observes, that “this goatsucker is full a third less than the _Caprimulgus Europæus_, and is remarkable for the uniformity of its markings, having no distinct white bars, or marks, either on the wings or tail.” FAMILY.—HIRUNDINIDÆ. 1. PROGNE PURPUREA. _Boie._ Hirundo purpurea, _Wils._ [Illustration: _Birds. Pl. 5._ _Progne modestus._ ] My specimens were obtained at Monte Video, (November) and Bahia Blanca, 39° S. (September) how much further southward this species extends I do not know. Jardine says, that in North America it migrates during summer as far as the Great Bear Lake, in Lat. 66° N.; it is mentioned by M. Audubon, at New Orleans, 30° N., and by Mr. Swainson, at Pernambuco, in 8½° S.; we may, therefore, conclude that it ranges throughout both Americas, but it is not found in the Old World. Wilson describes this bird as a great favourite with the inhabitants of North America, both European and Indian, who erect boxes and other contrivances near their houses for it to build in. At Bahia Blanca, the females were beginning to lay in September, (corresponding to our March): they had excavated deep holes in a cliff of compact earth, close by the side of the larger burrows inhabited by the ground parrot of Patagonia, (_Psittacara Patagonica_.) I noticed several times a small flock of these birds, pursuing each other, in a rapid and direct course, flying low, and screaming in the manner so characteristic of the English Swift, (_Hirundo Apus_, Linn.) 2. PROGNE MODESTA. _Gould._ PLATE V. Hirundo concolor, _Gould_, in Proceedings of the Zoological Society. _P. nitidè cærulescenti-nigra._ Long. tot. 6 unc.; _alæ_, 5¼; _caudæ_, 2¾; _tarsi_, ½.