OF NEW ENGLAND. 293 



CHAPTER II. 



SECOND ORDER. PICARI.E. 



THIS order is a " way-farer's home," established to receive 

 those birds who do not belong elsewhere (in science, a poly- 

 morphic group). The (North American) birds composing it 

 are characterized by the combination of a bill without any cere 

 or soft membrane, and one of the following features : tail- 

 feathers ten ; foot syndactyle by the union throughout of the 

 middle and outer toe ; front-toes two in number. There are 

 also certain internal and, other features which are more or less 

 characteristic. Either the bill or the toes always present cer- 

 tain peculiarities. 



There is an important element in classification, which is 

 often overlooked, that of latent features. These are frequently 

 undeveloped. For instance, the chief, and let us momentarily 

 suppose, the only, difference between the typical thrushes and 

 mocking-thrushes is in the tarsus, or so-called "leg." In the 

 latter group it is always scutellate (or divided into scales) at 

 least, in front ; whereas in the former thrushes, when adult, it 

 is " booted" (i. e. without scales, unless near the toes). Yet a 

 young robin with scutellate tarsi is no less a typical thrush ; 

 his tarsi are virtually u booted," and will become so upon normal 

 growth. Those of a young Cat-bird never will. Is not ab- 

 normal growth frequently due to the persistent latency of 

 normal features? As another example, the females of two 

 closely allied species may be exactly alike in coloration, size, 

 and structure. They may differ, however,- in the latent power 

 of producing distinct eggs ; they may differ less in the latent 

 instinct of building different nests, or still less in the latent 

 power of producing eggs, many of which contain the germs of 

 very distinct male birds. Hence the freshly laid eggs of two 

 species may be indistinguishable except in latent, undeveloped 

 features, though, since like produces like, they may be identi- 

 fied through the parent-birds. 



