504 



SYLVIAD^. 



ease against the perpendicular face of walls or rocks, by means of its 

 strong- toes and hooked claws, which are disposed in a totally different 

 manner from those of all other genera." * 



By the middle of August these wholly disappear, which is a month 

 or six weeks before the other species. It is said to inhabit the greater 

 part of the old continent, and has been found in some parts of America, 

 and at the Cape of Good Hope. 



SWIMMING OF BIRDS. — The superior velocity with which 

 aquatic birds swim under water has not wholly escaped notice ; but it 

 is not entirely produced by the action of the wings, which are some- 

 times used as fins to accelerate the motion, but is occasioned by the 

 pressure of the water above. In swimming- on the surface, a bird has 

 two motions ; one upward, the other forward, at every stroke of the 

 feet ; so that when covered with water, that force which was lost by the 

 upward motion is all directed to the progressive, by which it is enabled 

 to pursue its prey, or to escape an enemy with incredible speed. The 

 otter and water rat swim much faster under water than they do upon 

 the surface. 



SWINE PIPE.— A name for the Red Wing-. 



SYLVIA (Latham.) — *Warbler, a genus thus characterised. Bill 

 slender, rather awl-shaped, and straight ; but with the point of the 

 upper mandible slightly bent and notched ; lower mandible straig-ht ; 

 base more high than broad; nostrils at the sides of the base oval, 

 and partly covered with a membrane : leg-s having- the shank longer 

 than the middle toe ; toes three before and one behind, the outer toe 

 being joined at its base to the middle one ; wings with the first quill 

 very short, sometimes indeed wanting- ; the second and third nearly of 

 equal length ; wing coverts and scapulars short. * 



SYLVIAD.E (Vigors.)— Warbler kind, a family of Perchers, 

 (Insessores, Vigors.) 



