BIRDS 



117 



In all probability the naked head and neck of the turkey, 

 with the blue and red wattled skin and long fleshy process, are 

 to be regarded as exhibiting the inherited scars of a long 

 line of pugnacious ancestors. Darwin mentions that young 

 turkey cocks in fighting always seize hold of each other's 

 wattles, and he presumes that the old birds fight in the same 

 manner. It is known that in the wild state the males are 

 polygamous, and that the female attends exclusively to the 

 duties of incubation. Darwin considered that the fleshy 

 caruncle served as an ornament, supporting this opinion by 

 the fact that it is erected in courtship. But this fact is 

 better explained by the view that it owes its evolution to 

 congestion and hypertrophy caused by blows and tensions 

 received in fighting during the influence of sexual excitement. 

 On this view the turgescence or erection is due to the heredi- 

 tary association or correlation between the state of sexual 

 excitement and the congestion of the organ. 



The female turkey has to a certain extent inherited the 

 modifications of the head and neck acquired by the males. 

 It does not appear that the females themselves fight, and they 

 have not inherited the spurs. 



I have not found any mention in the literature of special 

 habits in the Mexican turkey which correspond to the tassel 

 of hair-like feathers on the breast of the males in that species, 

 but it is quite possible that there is some peculiarity of habit 

 corresponding to the character. 



In the Curassows of South America, genus Cmx t sexual 

 dimorphism occurs in some species but not in others. When 

 present it is not carried to an extreme degree. In both 

 sexes there is a median crest of semi-erect and curled feathers 

 on the head, which may possibly be related to courtship. In 

 some species, e.g. Crax caruncidata, there is, in the male only, 

 a large swollen knob at the base of the upper mandible, and 

 a wattle on each side of the base of the lower mandible, all 



