632 STERNA CANTIACA. 



fourth, which has twenty-two ; the webs with their margin 

 deeply concave. The chiws arc well arched, much com- 

 pressed, laterally sulcate, hluntish ; that of the hind toe 

 almost straight and conical. 



The plumage is rather compact, with a little silky gloss ; 

 on the lower parts rather blended ; the feathers mostly ellip- 

 tical and rounded ; but on the hind-head and nape elongated, 

 lanceolate, and acuminate. The wings are very long, surpas- 

 sing the tail by two inches, extremely narrow, and with 

 thirty-two quills ; the first quill longest, the other primaries 

 very rapidly graduated ; their shafts very large and strong, 

 their w-ebs narrow ; secondaries incurved, a few of the outer 

 emarginate, the rest obliquely rounded, the inner rather 

 pointed. The tail is moderate, or rather long, deeply forked ; 

 the two lateral feathers tapering, and longer than the medial 

 by an inch and three-fourths. 



The bill is black, but with the tips of a yellow horn- 

 colour for five-twelfths of an inch. The mouth internally is 

 dull flesh-coloured. The iris brown. The feet black, with a 

 tinge of brown; the soles of the toes dull reddish-yellow. 

 The upper part of the head is variegated with white and 

 black, the feathers being white, with a medial black spot or 

 patch ; but on the occiput and nape they are all bluish-black, 

 with white margins. There is a black crcscentic patch before 

 the eye. The throat, cheeks, neck all round, breast, abdo- 

 men, and sides, as well as the lower coverts of the tail and 

 wings, all white, with a delicate tinge of rose-colour, which 

 is little apparent until the feathers are put aside. The back 

 and upper surface of the wings arc light greyish-blue. The 

 out(!rmost four quills have the outer webs and rather more 

 than the same breadth of the inner blackish-grey. The shafts 

 of all the quills, the greater part of the inner webs, their tips, 

 and those of the scapulars, are white ; as are the upper tail- 

 coverts and tail. 



Length to end of tail 16 inches ; extent of wings 33| ; 

 bill along the ridge 2 j\ ; along the edge of lower mandible 

 3 ; wing from flexure 12^ ; tail b^ ; bare part of tibia -^ ; 

 tarsus -f- ; first toe ■^, its claw -^ ; second toe -j^^, its claw 

 ■^; third toe \^, its claw -^•, fourth toe -/V, its claw jV. 



