Family V. CYPSELINAE. SWIFTS.

Mouth opening to beneath the hind part of the eyes; bill extremely short, very broad at the base, compressed at the end; upper mandible decurved at the point, the edge inflected, with an indistinct sinus. Nostrils basal, approximate, oblong. Head large and depressed; neck short; body rather slender. Feet extremely short; tarsus rounded, destitute of scutella; toes extremely short, the three anterior nearly equal; hind toe very small, and versatile; claws strong, compressed, arched, very acute. Plumage compact; no bristles at the base of the upper mandible; wings extremely elongated, falciform, the first quill longest; tail of ten feathers. OEsophagus of moderate width, without crop; stomach oblong, moderately muscular, with a dense rugous epithelium; intestine short, and rather wide; no coeca. No inferior laryngeal muscles. Nest in crevices or holes, or attached to high places. Eggs elongated, white.