INTRODUCTION. 
lxxix 
much compressed, with the margin and gonys arched ; the nostrils basal, tubular, elevated above the culmen, short, 
opening with two apertures in front. Wings moderate, pointed, with the first quill nearly equalling the second, 
which is the longest. Tail moderate, broad, and rounded at the end. Tarsi shorter than the middle toe, laterally 
compressed, and covered with small scales. Toes long, the outer nearly as long as the middle, and the hind toe 
nearly in the form of a broad, short, pointed claw. 
Genus HALOBiENA, Is. Geoff. Southern Hemisphere. 
Gen. char. — Bill nearly as long as the head, more or less broad at the base ; the sides gradually compressed 
towards the tip, which is much elevated and arched, lengthened and acute ; the upper mandible furnished 
near its edge with laminated serrations, but few and inconspicuous as compared with Prion ; the lower mandible 
shorter than the upper, with the tip and gonys arched and acute; the nostrils basal, tubular, horny, elevated 
above the culmen, with the aperture double, frontal, and crescent-shaped. Wings long, pointed, with the first quill 
the longest, and the second scarcely shorter. Tail moderately long and truncated. Legs with the apical part of the 
thigh hardly naked. Tarsi shorter than the middle toe, laterally compressed, and covered with small scales. Toes 
long, with the outer as long as the middle toe, the inner shortest, and all united by a full web ; the lateral toes 
margined exteriorly, the hind toe in the form of a large subtriangular claw. 
Genus DAPTION, Stephens. Southern Hemisphere. 
Gen. char. — Bill much dilated, unguis small and weak; inter-ramal space wide and partially naked; oblique 
sulci on inner face of cutting-edge of mandible ; nasal tubes long. Wings long and pointed, with the second primary 
nearly as long as the first. Tail rather short, moderately rounded. Tarsi and toes as in CEstrelata. 
Genus CESTRELATA, Bonaparte. Chiefly confined to Southern Hemisphere. 
Gen. char. — Bill about as long as the tarsus, stout, compressed, higher than broad throughout, lateral 
outlines nearly straight, and converging to the unguis, which is much compressed ; unguis very large and strong ; 
outline of upper mandible very convex, rising almost immediately from the end of the nasal tubes, leaving but a very 
short and quite concave culmen proper ; outline of lower mandible nearly straight, the gonys a little concave ; 
sulci on both mandibles distinct. Wings rather long, extending beyond the tail when folded, and pointed ; the 
second primary nearly as long as the first. Tail, which is composed of twelve feathers, long and much produced, 
sometimes almost cuneate, usually much rounded. Tarsi moderately compressed, and about as long as, or a little 
less than, middle toe ; hallux short, sessile, conical, acute, and elevated. 
Genus OSSIFRAGA, Hombr. et Jacq. 
Gen. char. — Bill as long as, or rather exceeding, the tarsus, very robust ; the nasal case very long, depressed, 
carinated, the aperture small. Wings of moderate length, reaching to end of tail. Tail moderately long and 
rounded. Tarsi short, being much less than the middle toe without its claw, compressed, stout, reticulated. 
