452 THALASSIDROMA LEACHIL 



base of the ridge. The eyes of moderate size. The feet are 

 of moderate length ; the tibia bare to a small extent ; the 

 tarsus of ordinary length, very slender, covered with longitu- 

 dinally oblong scales. The hind toe is extremely diminutive, 

 "vvith a small, conical, acute claw ; the anterior toes long and 

 slender, the outer two about equal, the inner considerably 

 shorter, the second with eighteen, the third twenty-eight, the 

 fourth also tAventy-eight scutella. The interdigital mem- 

 branes slightly emarginate. The anterior claws slender, 

 compressed, pointed, slightly arcuate. 



The plumage is full, very soft, and blended ; the feathers 

 ovate. The wings are very long, exceeding the tail by half an 

 inch, narrow, and pointed, with twenty-four quills ; the pri- 

 maries tapering, but rounded ; the third longest, the second 

 two-twelfths shorter, and so much shorter than the first ; the 

 rest rapidly graduated ; the secondaries incurved, obliquely 

 rounded, the outer web being shortened ; the inner quills 

 straight and elongated. The tail long, deeply forked, of 

 twelve broad feathers, of which the medial are ten-twelfths 

 shorter than the lateral. 



The bill and feet are black ; the iris dark brown. The 

 general colour of the plumage is blackish-grey, tinged with 

 brown, especially on the breast ; the large scapulars grey at 

 the end, and narrowly edged with white ; the wing-coverts, 

 especially the secondary coverts and inner secondary quills, 

 are brownish-grey; the quills brownish-black; the featbers 

 on the hind part of the rump, some of those on the hind part 

 of the sides, and the outer lower tail-coverts, are white ; 

 some of the immediate upper tail-coverts are grey, and the 

 white feathers on the rump have the shafts black. The tail- 

 feathers brownish-black. 



Length to end of tail 7-f§- inches ; extent of wings 20 ; 

 wing from flexure 6jV ; tail 3^; bill along the ridge -j-^^ > 

 along the edge of lower mandible \^ ; bare part of tibia -^ ; 

 tarsus 1 ; hind toe -^, its claw -^ ; second toe -fj, its claw -^ ; 

 third toe -f^, its claw -^ ; fourth toe \^, its claw -f^. 



Female. — The female differs from the male only in being 

 somewhat less. 



