352 Synopsis of the Birds 



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. 



203. 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. 8Q.pl. 60. Jig. 4. 



Inhabits the tropical coasts of America : migrating during 

 summer to the coasts of the United States, where it breeds : 

 not rare in New- Jersey. 



G4. STERNA. 



Sterna, L. Gm. Briss. Lath. 111. 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. 



