THE OLASSiriCATION OJ BIBBS. 2S9 



XVIII. Struthiones. 



This last order contains all the Eatitse. 



It is absolutely impossible to arrange the Orders which make 

 up the Class of Birds in any linear series which shall express 

 their affinities. A few such groups may be placed in juxta- 

 position, and then follows an inevitable break. On the theory 

 of Eyolution all the various groups now existing are, as it were, 

 diverging twigs from small branches which sprang from larger 

 branches, and these from others, and so on, till we come to the 

 stem. It would manifestly be impossible, so to enumerate the 

 twigs of a tree in a linear series, that their linear succession 

 should indicate their relative relationships to the trunk whence 

 they all sprang. Just as difficult would it be to express the 

 genetic relations of Birds by placing them in any hnear series 

 whatever, and the same may be said of their deeper structural 

 resemblances even apart from the theory of Evolution. 



The first Order, Passeriformes, includes by far the greater 

 number of birds, and all those spoken of in our introductory 

 chapter as Passerine ^ birds. There are doubtless more than six 

 thousand six hundred species. 



Follovidng Mr. Seebohm, we divide this mass into three 

 groups, of approximatively equal rank, as suborders, and name 

 them : 1. Passeres, 2. Ewylcemi, and 3. TrochiU. The third 

 suborder includes all the Humming-birds and no others. The 

 second suborder takes in only the Broadbills and their allies ^ 

 while the first suborder includes all the other Passerine Birds. 

 The characters of these groups are as follows : — 



Subclass! CAEINAT^. 



Order I. PASSERIFOEMES. 

 Perching-birds, the young of which are born helpless and 

 need to be fed in the nest for ipany days, yet which hardly 

 ever pass through any downy stage ^. The hallux is always 

 present as a hind toe, is well-developed, separably moveable, and 

 furnished with a larger claw than the others. "Wing-coverts 

 somewhat few in number and rather small ; greater coverts 



' See ante, p. 131. ^ See ante,yi. 77. 



' Thickly eovered with down only in the Lyre-bird (Menura), 



S 2 



