NATURAL SCIENCES OF PHILADELPHIA. 43 



in September (a few probabl>' somewhat earlier), and is ver}^ com- 

 mon until December. A large number shot in the middle of Sep- 

 tember were in the same condition of plumage as T. regius was 

 at the same time. The species maj' be marked out among its allies 

 by its size, its singular!}- trim shape, conspicuously black, /o»<7 bill, 

 yellow-pointed, and a genersA whitemess ; the mantle being paler 

 than in anj^ of the others. Specimens, even in the fall, frequently 

 show a ros}' blush of the under plumage, much like that generally 

 supposed to characterize 2\ elegans of the California coast. 



The difference in the pattern of the coloration of the primaries 

 of tliis bird, that was noted in my "Review" as separating the 

 species (or whatever it is to be considered) from the European T. 

 cantiacu)?^ has not failed in a single instance that has come to my 

 knowledge. No reliance, however, can be placed upon thej'ellow 

 tip of the bill as a character ; this varies from nothing (in imma- 

 ture specimens) up to a third, or nearly, of the total length of the 

 bill, and no two specimens show exactly the same line of demar- 

 cation between the 3'ellow and the black. Specimens, as usual 

 in this family, differ much in size, and particularly in the length 

 and stoutness of the bill. The feet are always black, as in T. 

 regius. 



Sterna hirundo. 



Very common, but only during the migration. Arriving from 

 the south early in April, the}- all pass on during the following 

 month. The}'^ are abundant again in September and October, 

 perhaps a little earlier and later, but I identified none except 

 during these months. In the spring they are scarcel}' to be told 

 with certainty, unless shot ; but in the fall they are conspicuous 

 by the fact that they retain the black pileum, at least as long as 

 they remain here. It has been stated, upon eminent authority, 

 that this species never loses the black on the head ; and, although 

 I do not confirm this from examination of specimens taken in 

 the depth of winter, my observations until the end of October 

 support it, and I do not remember to have seen in any museum 

 a "Wilson's tern without the feature in question. Numbers shot 

 here in September had completed the winter plumage, and were 

 newly feathered, except on the crown, where the black looked worn 

 and faded, but was still unmixed with white, except a few specks 

 on the extreme front. I presume that the change on this part of 



isn.] 



