26 ANATOMY OF VERTEBRATES. 



Skimmers, Gulls, and Terns, the sternum has two shallow notches 

 on each side the posterior margin. In the Petrels and Albatross 

 the posterior border is feebly incised or entire and the sternum ac- 

 quires great breadth, especially in the Albatross. The keel reaches 

 the furculum in all the Longipennate family. In the PelecanidcB, 

 confluence of the two bones usually here occurs ; there is a pair of 

 shallow posterior emarginations. In the Lamellirostrals the ster- 

 num is both large and long, boat-shaped, with extensive costal 

 borders ; the keel is of moderate depth, with almost straight free 

 borders, excavated for tracheal folds in some swans ; there is a 

 short notch or small foramen on each side the broad posterior 

 margin in all the Sifters ; the manubrium curves downward in 

 many. The Flamingo's sternum is given in fig. 14, c. The fore- 

 Q-oino- diversities of sternal structure in the web-footed birds indi- 

 catc from how many types they have been derived, and shows the 

 artificial character of the webbed-foot. 



The same testimony is borne by the breast-bone of the long- 

 legged birds, from which, in some instances, the species have 

 been detached when the truer affinities were sufficiently strongly 

 marked, as, e. g., the Flamingo to the Sifters or Lamellirostrals ; 

 the Secretary Bird to the Vultures ; and the Couas to the Cuc- 

 koos. In the long and narrow sternum of the Coots and Rails 

 the two posterior notches are deep, with the outer boundary the 

 longest, and Bracliyiiteryx shows a third intermediate shallow 

 notch. 



The Ibis and Spoonbill have a four-notched sternum ; the Ad- 

 jutants and Herons have a two-notched one ; the notches are short 

 in both. Peculiarities in the breast-bone of certain Cranes have 

 already been noticed. The Woodcock (^Scolopax) has a pair of 

 notches, mth the outer boundary slender and shorter than the 

 broad intermediate tract ; the Gambets ( Totamis), Avocets, Sand- 

 pipers (^Trinf/f(), Curlews (^A^umc7iius), Pratincoles (^Glareola), 

 have the four-notched sternum. In the Godwits {Limosa, Helias), 

 the medial notches are almost obsolete, and the lateral ones wide. 

 The ^ Thiok-kwdQ^^ (^(Edicnemus) and Bustards (Otis) have the 

 four- notched sternum, the notches beiug small. 



In the Gallinaceous group of Basores, the four posterior notches 

 are so wide and deep as to reduce the bony parts of the sternum 

 almost to five slender processes, diverging from a short and 

 broad anterior stem, and the points of ossification are multi])licd 

 accordingly. The middle process is the broadest, and from it is 

 developed the keel, of which, in some ( Ortyx, Perdix), it seems 

 to be almost wholly composed. As the median pair of notches 



