DICHOTOMY. 113 



Dichotomy may, not infrequently, affect other digits ; 

 thus in fig. 6 1 a chick is represented with two bifid 

 toes and partial duplicity of the left leg. Birds with 

 these accessory parts may live and attain the adult 

 condition. 



Supernumerary legs are very common in birds, indeed 



FIG. 61. A Chick with two dichotomized digits 

 and a supernumerary leg. 



almost every poultry breeder has seen examples, yet 

 accessory wings are very rare. One specimen only is 

 known to me, a dove, preserved in the museum of the 

 Royal College of Surgeons (fig. 62). This bird has an 

 accessory wing growing from the lower part of the 

 sternum, 



9 



