THE RELATIONS OF THE SEXES 149 



of many of the Pigeon tribe. Herein tlie bird inflates the 

 gullet, and more especially the crop, and this done, proceeds to 

 pay his vows of everlasting constancy to his mate by keeping 

 up an incessant "cooing" accompanied by a succession of 

 most courtly bows. The great Australian Bustard {Eupodotis 

 australis) similarly inflates its gullet. "The premonitory 

 symptoms," says Dr. Murie, " observable when [this] Bustard 

 is about to exhibit himself in the pride of lust ... is a slight 

 swelling of the infra-mandibular portion of the throat, while 

 the head is thrown upwards. Immediately afterwards the neck 

 swells, and the feathers of the lower parts concomitantly bulge 

 out and descend gradually downwards in the form of a bag) 

 oftentimes nearly reaching the ground. 



" If the paroxysm is a strong one, then the tail is shot up- 

 wards and forwards over the back, the rectrices coming almost 

 in contact with the neck. 



" In this peculiar attitude, with bloated neck, hanging, baggy 

 chest, elevated tail, and stiff, stilt-like legs, the creature struts 

 about in a somewhat waddling manner, the elongated pouch 

 swaying to and fro. The feathers of the throat start out on 

 end, those of the depending sac are also raised but less upright. 

 While all this has taken place the bird seems to have gulped in 

 air, or rather, with partly opened gape, to have taken a long, 

 deep and forced inspiration. 



"The acme of inspiratory effort and strange attitude at- 

 tained, the Bustard begins to snap the mandibles together in a 

 loud manner and utter a series of cooing sounds for a short 

 interval of time. Usually and more frequently he struts 

 towards the female Bustards in a most dignified manner. . . ." 



No less remarkable are the displays of the American Ruffed- 

 grouse {Tympanuchus americanus) and the Frigate-bird. 



In the case of the Ruffed-grouse the inflatable sac appears 

 to be formed by specially modified air-sacs running up the neck. 

 But the eff"ect is heightened by the fact that the featherless 

 spaces which normally occur on each side of the neck are 

 deeply pigmented with bright yellow, so that, when the sacs 

 are distended with air the bare yellow skin is thrust out in the 

 form of a pair of globular swellings, which have been compared 

 to oranges. Above these sacs have been developed a frill of 

 long narrow feathers which during the time that the sacs are 



