128 NATURAL HISTORY 



whether the latter be much of a songster f but in this matter 

 I want to be better informed. The former has a variety of 

 hurrying notes, and sings all night. Some part of the song 

 of the former, I suspect, is attributed to the latter. We have 

 plenty of the soft-billed sort; which Mr. Pennant had entirely 

 left out of his British Zoology, till I reminded him of his 

 omission. See British Zoology last published, p. 16. x 



I have somewhat to advance on the different manners in 

 which different birds fly and walk ; but as this is a subject 

 that I have not enough considered, and is of such a nature as 

 not to be contained in a small space, I shall say nothing- 

 farther about it at present. 7 



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. &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 clioro, 



" Mire sagaces falleret hospites 



" Discrimen obsctirum, solutis 



" Crinibus, ambiguoque vultu." Hon. 



* See letter xxv. to Mr. Pennant. * See letter xlii. to Mr. Harrington. 



