480 Mr. N. A. Vigors on the Natural Affinities 



the order. Keeping, then, these characteristic peculiarities of 

 the Rasores steadily in view, we may draw the conclusion that 

 the typical groups will be those which, in reference to external 

 character, may be distinguished by the weak conformation of 

 the hallux or hind toe, and the height on which it is articulated 

 upon the tarsus. The aberrant groups will in like manner be 

 either those whose hind toes are more developed, and articulated 

 lower down upon the tarsus, and which thus retain most closely 

 the habits of the Perchers ; or those which, though they possess 

 no hind toe, and thus seem to partake most strongly of the typi- 

 cal character of the order, are yet found to deviate from it in the 

 length of the tarsus, by which character they lead off to the JVa- 

 ders. Following these views of arrangement, we may group the 

 Rasores as follows, placing the typical families in the centre* : 



Columbida, Leach. 

 Phasianida. 

 TetraonidcB, Leach. 

 Struthionida. 

 CracidcE. 



I have already observed, when speaking of the affinities which 

 connect the orders of Birds together, that the Columbida form the 

 passage from the Insessores to the Rasores by their habits of perch- 

 ing and their powers of flight. The hind toe is articulated as in 

 the Perchers, and their tarsi are shorter, more particularly in the 



* Or, with reference to their normal and aberrant groups, thus ; 



•ip. 



>ta; tarsis J 

 'atis. . . . [^ 



Normal group. 



Halluce brevi, amota; tarsis f Phasianidce. 



praecipue calcaratis .... "j^ TetraOJlida. 



Aberrant group. 



Halluce aut nuUo, aut plus vel T Stniihiotlida. 



minus terrae incumbente ; J CvacidiE. 



tarsis nunquam calcaraUs. (^ ColumUda. 



earlier 



