552 



ZOOLOGY. 



grasping, one toe projecting backward, while the bill is horny, 

 usually sharp conical, according to Coues. Various as are 

 the shape of the wings, they agree in having the great row 

 of coverts not longer than half the secondaries ; the pri- 

 maries either nine or ten in number, and the secondaries 

 more than six. The tail, extremely variable in shape, has 

 twelve rectrices (with certain anomalous exceptions). There 

 is but one common carotid artery, and the sternum is very 

 uniform in shape. Their high physical irritability is co- 

 ordinate with the rapidity of their respiration and circula- 

 tion ; they consume the most oxygen and live the fastest 

 of all birds (Coues). 



There are two groups of 

 Passerine birds, differing in 

 the structure of the lower 

 larynx ; in the first ( Clama- 

 tores) the vocal organs are 

 more or less rudimentary, 

 the species not being singers, 

 while in the second and 

 higher division (Oscines) the 

 lower larynx is so developed 

 that most of the species ex- 

 cel as singers. In the sing- 

 ing birds the vocal apparatus 

 (syrinx), or lower larynx, is 

 situated next to the lungs at 

 the end of the windpipe, with a muscular apparatus formed 

 of five or six pairs of muscles, whose action varies the 

 tension of the vocal cords and narrows or widens the 

 glottides, which are elastic folds of the mucous membrane. 

 A fold of the tympanal membrane of the syrinx, called the 

 membrana semilunaris, projects inward. 



Representatives of the Clamatores are the Acadian fly- 

 catcher, the wood pewee, the pewee or phcebe-bird, and the 

 kingbird (Fig. 476). The last, sometimes called the bee- 

 martin, Coues tells us, destroys a thousand noxious insects 

 for every bee it eats. The lyre-bird (Fig. 477) is also a 

 member of this group. 



Fig. 476. Kingbird. From Cones' Key. 



