60S GAVIA SABINI. 



slightly concave, the sides erect and nearly flat, the edges 

 sharp and inflected, the tip very narrow. 



The feet are of moderate length, rather slender ; the tibia 

 bare for nearly half an inch ; the tarsus compressed, with 

 numerous anterior scutella ; the hind toe elevated and very 

 small, with a minute blunt claAv ; the anterior toes slender, 

 with numerous scutella, the second much shorter than the 

 fourth ; the lateral slightly margined ; the interdigital mem- 

 branes with their margin slightly concave. The claws are 

 short, slightly arched, compressed, obtuse, that of the middle 

 toe with the inner edge expanded. 



The plumage is soft, close, and blended, on the back and 

 wings rather dense. The wings are very long, exceeding the 

 tail by about two inches, rather narrow, and pointed ; the 

 primaries tapering to a rounded point, the first longest, the 

 second slightly shorter, the rest rapidly decreasing ; the outer 

 secondaries obliquely rounded, the outer web not reaching to 

 the tip ; the inner secondaries elongated. The tail is of 

 moderate length, deeply emarginate or slightly forked. 



The bill is black to a little beyond the nostrils, then 

 yellow ; the angles of the mouth, its interior, and the edges 

 of the eyelids vermilion ; the feet black. The head and upper 

 part of the neck all round blackish-grey, that colour more 

 extended on the throat than on the nape, and terminated by 

 a ring of deep black. The rest of the neck, all the lower 

 parts, the upper tail-coverts, and the tail, pure white. The 

 back and upper surface of the wings bluish-grey ; the edge of 

 the wing from the flexure black ; the first five primaries, 

 their shafts included, black, but with half of their inner webs 

 to near the end, and the tips, white. The secondaries and 

 their coverts are largely tipped with white. 



Length to end of tail 14 inches ; extent of Avings about 

 3'2; wing from flexure 11^ ; tail to end of lateral feathers 5; 

 bill along the ridge lyV ; along the edge of lower mandible 

 1^; its height at the knob -,\ ; tarsus 1} ; middle toe 1, its 

 claw j\. 



Female. — The female is similar to the male, but some- 

 what less. 



