Synopsis of the Birds 
362 
the lower. Breed socially on the rocks, or on sandy beaches, 
without any preparation ; lay but once a year ; eggs 3, oval. 
Voice strong, harsh, screaming. 
Chiefly tropical : found in all longitudes. Composed of 
but three species. 
283. Rhincops nigra, L. Black ; beneath white ; bill and 
feet red, the former black at the point. 
Black Skimmer , or Shearwater , Rhincops nigra , Wils. Am. 
Orn. p. S9.pl. so. fig. 4. 
Inhabits the tropical coasts of America : migrating during 
summer to the coasts of the United States, where it breeds i 
not rare in New-Jersey. 
64. STERNA. 
Sterna , L. Gm. Briss. Lath. III. Cuv. Vieill. Temm. Ranz . 
Sterna , Thalasseus , Sternula , Hydrochelydon , Boie. 
Bill longer than the head, robust, straight, compressed, 
more or less subulate, acute ; edges sharp, bent in for a 
space beyond the middle ; upper mandible more or less 
curved at the point, never hooked; lower equal to the upper 
slightly angular beneath : gape wide : nostrils somewhat dis- 
tant from the base, lateral, longitudinal, linear, pervious : 
tongue moderate, slender, cleft and acute at tip. Head 
and neck moderate : body elongated, slender, compressed. 
Feet small; naked space on the tibia well marked; tarsus 
shorter than the middle toe : anterior toes slender : the 
webs more or less indented ; lateral toes margined exteriorly 
with a narrow membrane ; outer toes longer than the inner ; 
the middle one longest; hind toe shorter than a phalanx of 
the middle toe, touching the ground merely at tip; anterior 
nails curved, acute ; middle one thrice as long as the lateral ; 
hind nail extremely short. Wings very long, when folded, 
crossing each other, extremely falcate, acuminate ; first pri* 
mary longest. Tail rather long, generally forked. 
