SEX OF ANIMALS. 93 



No doubt the reason why the sex of birds in their first 

 plumage is so difficult to be distinguished is, as you say, 

 " because they are not to pair and discharge their parental 

 functions till the ensuing spring." As colours seem to be the 

 chief external sexual distinction in many birds, these colours 

 do not take place till sexual attachments begin to obtain. And 

 the case is the same in quadrupeds ; among whom, in their 

 younger days, the sexes differ but little ; but, as they advance 

 to maturity, horns and shaggy manes, beards and brawny 

 necks, &c. strongly discriminate the male from the female. 

 We may instance still farther in our own species, where a beard 

 and stronger features are usually characteristic of the male 

 sex ; but this sexual diversity does not take place in earlier 

 life ; for a beautiful youth shall be so like a beautiful girl, that 

 the difference shall not be discernible : * 



Quern si puellarum insereres choro, 

 Mir6 sagaces falleret hospites 

 Discrimen obscurum, solutis 



Crinibus, ambiguoque vultu. HOR. 



during the love season, in a circling manner, supporting itself with both 

 wings angularly elevated, in which position it keeps them until it is about 

 to alight. Now and then, during these circular flights, the tips of the 

 primary quills of each wing are made to strike against each other, 

 producing a sharp rap, which may be heard at a distance of thirty or forty 

 yards. Before alighting, the passenger pigeon, like the Carolina parrot, 

 and a few other species of birds, breaks the force of its flight by repeated 

 flappings, as if apprehensive of receiving injury from coming too suddenly 

 into contact with the branch, or the spot of ground, on which it intends 

 to settle." 



Mr Audubon calculates that the passenger pigeon must travel at the 

 rate of a mile in a minute, a velocity which would enable one of these 

 birds to visit the European continent in less than three days. 



* There is a remarkable physiological fact in the animal economy, 

 that of the females of many species assuming somewhat of the character 

 of the male when they become aged. This obtains in a strong degree in 

 many animals, and something similar takes place in the human species ; 

 for example, that increase of hair observable in the faces of many women 

 advanced in h'fe, is certainly an approximation towards a beard, which is 

 one of the most distinguishing secondary properties of man. It is also 

 well known that old mares approach the form of the horse, in the 

 thickening of the crest. 



Dr Butter, of Plymouth, has satisfactorily proved, that our female 

 domestic fowls have all a tendency to assume the male plumage at an 

 advanced period of their lives, so as to make them resemble the cock of 

 their own species. In illustration, he states, that " Mr Corham, at 

 Compton, near Plymouth, has, for a long series of years, possessed an 

 excellent breed of game-fowls, the cocks of which are of a beautifully 

 dark-red colour, and the hens of a dusky brown. One hen of this 



