NATURAL SCIENCES OP PHILADELPHIA. 543 



I 1 is bright yellow at the tip for exactly the same distance as is the bill of 

 " Havelli;" but the base, for nearly a third of the length of the bill, appears to 

 have been in life bright orange yellow, so that only the middle of the bill is 

 left black ; whereas, in " Havelli," the bill is black from its yellow tip quite to 

 the base of the upper mandible, and only a small space on the under mandible 

 is left yellow. The front and crown are white, passing into light pearl blue on 

 the nape, exactly as in " Havelli ;" the circumocular fascia also exists, but it 

 is somewhat narrower than in that species. The other upper parts are of 

 exactly the shade of Forsteri or "Havelli;" but this color extends around the 

 sides of the neck quite to the throat, and occupies the whole under parts of 

 the bird, not even excepting the under tail-coverts, whereas in " Havelli " and 

 Forsteri, the color of the same parts is nearly or quite pure white. The rump 

 is white, as in both those species. The tail is elongated ; exactly intermedi- 

 ate between a full plumaged summer Forsteri and " Havelli ;" it has precisely 

 the color of the latter, the inner web of the lateral feather being somewhat 

 lighter than in the former. The wings, in their markings and length, are iden- 

 tical with those of either Forsteri or " Havelli;" the tarsi and toes are fraction- 

 ally of the same length, and appear of about the same color in the dried skin. 



The differences therefore between " Havelli" and " Trudeaui," lie entirely in 

 the following features : 1st. The bases of both mandibles are orange yellow for 

 nearly half their length in "Trudeaui" while in "Havelli'''' a very small portion of 

 the under mandible only is light colored. 2d. The color of the back extends 

 indiluted over the whole under parts of "Trudeaui," while the same parts in 

 " Havelli " are white. 



The greater slenderness of the bill, and the shorter tarsi, given by Audubon 

 as characteristic of " Trudeaui" in comparison with " Havelli" do not exist, 

 provided the specimens before me exhibit the characters of the latter. Indeed, 

 a comparison of fourteen specimens of Forsteri, three of "Havelli" and the 

 single " Trudeaui" shows the three to be surprisingly similar in every detail 

 of size and proportions ; the bills and tarsi particularly, hardly differing as 

 much in length a3 do these parts in different individuals of hirundo or macroura. 



Should the color of the bill and of the under parts of " Trudeaui," more par- 

 ticularly the latter prove constant, they would be abundantly sufficient to 

 separate it from any other species. The only question is, whether the speci- 

 .11 en under consideration is not in an entirely accidental and abnormal state of 

 plumage, to be placed in the same category with albinism, melanism, Ac. 

 Although Audubon states that he saw other individuals like the present speci- 

 men, it appears to be the only one ever actually examined. The question is 

 one of great interest, but one of which, unfortunately, we are no nearer the 

 positive solution than we were twenty years ago ; and I am therefore obliged 

 rem in medio relinquere. 



"Sterna Havelli Aud." 



Sterna Havelli, Audubon, Orn. Biog. v. 1839, 122. Lawrence, Gen. Rep. Birds, 

 1858,861. 



So accurate a description of the winter plumage the only one known of 

 this supposed species has been given by its discoverer, that it is unnecessary 

 here to repeat it. A discussion of the essential characters assigned to it, to dis- 

 cover exactly what are its claims. to specific distinction, may be given. 



It is not a little singular that, of a species recognized for more than twenty 

 years, the nuptial plumage should be still quite unknown. I am not aware 

 that a specimen which could be referred to this species ha9 ever been taken ia 

 spring or summer. There can be no doubt, however, that at that season it 

 . obtains the black pileum common to all the species of the genus, with, proba- 

 bly, not even the exception of " Trudeaui." A specimen before me, which agrees 

 more closely than any other with Audubon's plate and description, has the 

 ciown and occiput very noticeably variegated with black; this color, indeed, 



1862.] 



