CHAPTER I. 



FIRST ORDER. PASSERES. 



These birds " are tlie typical Insessores^ as such represent- 

 ing the highest grade of development, and the most complex 

 organization, of the class. Their high physical irritability is 

 coordinate with the rapidity of their respiration and circula- 

 tion ; they consume the most oxygen, and live the fastest, of 

 all birds." ^^ All our forms, at least, are characterized as fol- 

 lows : bill without a cere, or a soft basal membrane ; front toes 

 never only two, or united throughout (i. e. two of them), hind 

 toe never wanting ; tail-feathers twelve. This group may be 

 characterized, as a ivhole, as the only order of birds of which 

 all the species invariably build a nest in which to lay their 

 eggs. Among the birds breeding in Massachusetts there is no 

 exception to this rule, except the parasitic Cow-bird. 



" Passeres, corresponding to the Insessores proper of most 

 ornithologists, and comprising the great majority of birds, are 

 divisible into two groups, commonly called suborders, mainly 

 according to the structure of the lower larynx. In one this 

 organ is a complex muscular vocal apparatus; in the other the 

 singing parts are less developed, rudimentary, or wanting. 

 In the first, likewise, the tarsus is normally covered on either 

 side with two entire horny plates, that meet behind in a sharp 

 ridge ; in the other these plates are subdivided, or otherwise 

 differently arranged. This latter is about the only external 

 feature that can be pointed out as of extensive applicability ; 

 and even this does not always hold good. For example, 

 among our birds, the Larks (Alaudidce')^ held to be oscine, 

 and certainly to be called songsters, have the tarsus perfectly 

 scuteUate behind." ^^ 



19 Dr. Coues ; Key to North American Birds. 



