88 NOTES AN.U 



from the 12th to the 20th of May when they go to the north ; that irom June till 

 August, the male changes his colour, and assimilates the female, when they re- 

 tire to the south j that the organs of birds, by which the sex is detected, are, in 

 autumn, no larger than the smallest pin's head, and that the spring increases 

 them a hundred fold, which led to the error of Catesby, when he applied the 

 anatomical knife. (Wilson's Ornithology, vol. 2.) That in October they visit 

 Jamaica suid Cuba, and return to the continent early in the spring. This is a 

 most satisfactory solution of all the doubts which have existed on this subject. 

 When dr. Barton states, that the females exclusively make their appearance in 

 Philadelphia, about the 20th of August, the male bird has then changed its colour, 

 and botli sexes are on their southern journey. When Catesby and Bartram say, 

 that the females only appear in autumn in Carolina, it is only a continuation of 

 the southern progress of both sexes identified in external appearance. When 

 Catesby made his dissections, and concluded that all his subjects were females, 

 it was in September, when the soxual distinctions are not palpable ; but when 

 they became so in the spring, he had no difficulty in recognising both male and 

 female. 



I might extend these remarks, on similar topics of inquiry, but I have already 

 occupied too much ground; these slight sketches will indicate what an interest 

 ing and spacious field of investigation might be explored. 



NOTE 19. 



In 1810 I saw a great number of ravens on the borders of the beautiful lake 

 Canadesaga, or Seneca, near the village of Geneva, and was told that no crows 

 had made their appearance in that part of the country. Michaux, in his travels 

 before quoted, observes, that the crows have not yet been seen in Tenessee ; but 

 It is probable that their appearance is only deferred, for they are already very 

 destructive in Kentucky. The gray rats of Europe in like manner follow the 

 establishments of the whites ; they have not yet penetrated into Cumberland in 

 Tenessee ; they make their appearance a few years after the country has been 

 inhabited. 



