PASSERES. 65 



ORDER II. 



Pas SERES. 



The birds belonging- to this order are frequently 

 termed Insessores^ or Percbers^ seeing that tliey are^ 

 for tlie most part^ expressly adapted for a life 

 among the branches of trees or bushes, upon which 

 they perch, and hop from twig to twig. Their feet 

 are, consequently, more or less constructed for this 

 purpose. Their legs are of moderate length, and 

 the toes, usually placed three in front and one 

 behind, are provided with sharp and slender claws,, 

 and of sufficient strength to secure the bird firmly 

 on its perch. This arrangement of the toes is, 

 however, subject to certain exceptions, as we shall 

 see when speaking of particular species. There are 

 other general characters, which, taken in conjunction 

 with those given above, will, in doubtful cases, 

 frequently enable us to determine whether a bird 

 belongs to this order or not. The tarsi are covered 

 with shield-like horny plates, so disposed that while 

 in front there are several of these pieces, the back 

 of the leg is usually covered by a single long shield. 

 The outer toe of each foot is generally united to 

 the middle one for a greater or less extent, some- 

 times only at the base, but occasionally nearly to 

 the extremity. The claws with which the toes are 

 armed are either of moderate length or very long 

 and slender. The wings are well developed, so that 

 many of the Passerine races fly remarkably well. 

 The primary quill-feathers in the wings are usually 

 ten in number, and the number of quill-feathers in 

 the tail is likewise generally ten. 



This Order is divided into the following Tribes.*^ 

 * See " Animal Creation," page 418. 



