194 ON SYSTEMATIC ZOOLOGY. 



be paid to such matters ; their advocates, very judi- 

 ciously, do not insist on such considerations, nor do 

 they attempt to point out in what way nature gradually 

 passes from one group to another. That the reader, 

 however, may be better able to judge for himself on the 

 merits of a binary or dichotomous arrangement, we here 

 present him with a table of the class of birds, as given 

 by one who is, we believe, the only advocate of dicho- 

 tomy* : 



Order I. FISSIPEDES. Land Birds. Toes free, and formed for grasping 



or walking. 



Tribe 1. TERRESTRES. Tibial joint, feathered. 

 Sect. 1. AMBULATORES. Three toes directed antially, and fitted 

 for walking or grasping. 



("GALLINAD-E. Bill arched from the 

 I. Nostrils hid under an | base; eggs numerous. 



arched covering, wings-{ COLUMB A \>JE. Bill swollen at the 



short. 



II. Nostrils exposed, or hid 

 only by feathers. 



Sect. 2. SCANSORES. Two toes 



base, nearly straight, and sub- 

 ulate towards the extremity. 

 ACCIPITRES. Bill and claws 

 strongly hooked, limbs strong, 

 tongue emarginate. Females 

 largest. 



PASSERES. Bill nearly straight 

 at the gape, no cere. Males 

 largest. 



directed antially, and fitted for 



climbing trees. 

 Tribe 2. GRALL.E. Waders, lower end of the tibial joint and tarsus 



naked. 



Order II. PALMIPEDES. Water Birds. Toes webbed to their extremity, 

 and formed for swimming. 



(251.) The value of a theory can only be determined 

 when we bring it into practice, and when, by following 

 it down to its lowest details, we can judge how far it 

 is agreeable with our ordinary conceptions of nature, 

 and how far it answers the purposes of arrange- 

 ment. With this view let us examine the foregoing 

 table, which we must presume has been drawn up by 

 one having " distinct conceptions on positive and nega- 

 tive characters ;" and let us do this, both with reference 

 to its natural order, and to the help it gives for the de- 

 termination of a species. We need not be -long detained 

 on the first, for it is difficult to name any two families 

 of birds more unlike each other than the pigeons (Co- 

 lumbadai) and the eagles (Accipitres) , which are here 

 brought together. A greater violation of nature was 



* Dr. Fleming's Philosophy rf Zoology and British Animals. 



