;jl2 TROPICAL WILD LIFE IN BRITISH GUIANA 



FIG. 105. DEVELOPMENT OF THE THIRD DIGIT OF THE ANI 

 a. Partly developed embryo. b. Twenty-four hours before hatching. c. Adult. 



DIGITUS 



The bone structure of the digitus presents several in- 

 teresting features. Two points especially stand out on ac- 

 count of their being peculiar to this bird or its near rela- 

 tives. First is the curious horizontal flattening of the third 

 metacarpal. It appears ahnost to be divided into two bones 

 running parallel to each other and connected by a very 

 thin transparent layer of bone. At the proximal end, where 

 it is ankylosed to the second metacarpal, it is broadly flat- 



