824 U. S P. RB. R. EXP. AND SURVEYS—ZOOLOGY—GENERAL REPORT. 
Sub-Family PROCELLARINAE.—The true Petrels. 
Cu.—The bill more or less strong, compressed, tip much hooked and pointed ; the nostrils tubular toa greater or less extent, 
and situated on the basal part of the culmen. Generally of medium or small size, wandering in their habits, and capable of 
sustaining themselves on wing for a great length of time. 
In this sub-family there are five genera which belong to North America, with the following 
characters : 
1, Procetnarra.—Bill rather stout, strong, curved at the end; lower mandible with a 
lateral groove; nostrils covered by an elevated sheath, opening forwards, divided by a 
thin septum, and situated near the base of the culmen; tarsi strong and rather short. 
2. Daptron.—Bill short, broad, compressed near the tip which is curved and acute; 
nostrils at the base of the culmen, opening forwards, and covered with a flattened 
sheath ; tarsi slender. 
3. THaLiasstpromA.—Bill short and slender; nostrils situated at the base of the culmen, 
tubular and prominent ; tarsi slender and very long. 
4, FrecerraA.—Bill small; nasal tubes short and recurved, situated at the base of the 
culmen ; tarsi long, toes strong, nails flattened. 
5. Purrinus.—Bill long, rather slender; nostrils at the base of the culmen, covered 
with a sheath, which is elevated at the opening, where the apertures are separate ; 
tarsi rather long and compressed. 
PROCELLARIA, Linnaeus. 
Procellaria, Linn. Syst. Nat. 1746. 
Cu.—Bill rather short, strong, somewhat compressed near the tip, which is much curved and acute; nostrils tubular, of 
different lengths, opening forwards and divided by a thin septum ; lower mandible grooved laterally and with the tip much 
arched ; wings long and pointed, first quill the longest ; tail rounded or cuneate ; tarsi strong and rather short ; toes long and 
united by a full web ; in place of the hind toe a triangular claw or spur. 
They are found mostly in the higher latitudes, are strictly marine, seldom visiting the 
neighborhood of the shore. They feed on fish, and the flesh and blubber of cetaceous animals. 
They are rapid in their manner of flying, and graceful in their movements. 
Five species belong to North America, which may be characterized thus: 
Large; bill dark yellow; nasal case long; back and wings brown, mottled with dull 
white ; under plumage white; legs and feet dusky yellow.....,.sccecseeseeoes P. gigantea. 
Middle size; bill yellow; back and wings pale grayish blue; below white; legs and feet 
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Middle size; bill yellow; nasal case with the ridge carinate; back and wings light 
greyish blue; under parts white; legs and feet yellow..........sseccoserseecreerd « Pacifica. 
Middle size; bill yellow, with the nasal case and tips of both mandibles black; back 
and wings greyish blue; below white; legs and feet yellow........ we BP. tenutrostris. 
Of rather small size; bill black; back and wings dark brown; under plumage 
white; tarsi and base of feet pale yellow; terminal two-thirds of feet blackish 
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