NATURAL SCIENCES OP PHILADELPHIA. 



547 



web of first primary black; inner webs of the others somewhat hoary, with 

 well defined white spaces. Tail white, different from the back, its lateral 

 feather moderately produced (average 6 inches in length) ; its outer web gray- 

 ish-dusky, inner white. Legs moderate; length of tarsus about -80 of an 

 inch; light vermilion-red. Length of tarsus, middle toe and claw 1-75 inches. 



S. macroura. Bill (average) 130 along culmen ; depth at base -30; slender. 

 Bill wholly deep carmine-red. White space between eye and cutting edge of 

 upper mandible narrower than in Mr undo. Under parts decidedly plumbeous, 

 extending from vent to throat, both of which become abruptly white. Prima- 

 ries as in hirundo. Tail with the elongation of Forsteri, or rather exceeding it, 

 (average 7-50 inches), and the color of hirundo. Legs very short and slender; 

 length of tarsus (average) -65 of an inch ; deep vermilion, almost lake. 

 Length of tarsus, middle toe and claw, about 1-50 inches. 



Comparison of the young of the year of S. Forsteri and hirundo. The bill and 

 feet constantly present differences proportional to those which exist in the 

 adults, as regards length and stoutness. The bill of hirundo is more decidedly 

 yellowish at the base of the lower mandible than in that of Forsteri; and the 

 feet are clear yellow instead of being tinged with dusky. The mottled and 

 Tariegated crown and upper parts are much the same in bo'h ; and the markings 

 of the quills quite identical. The tail, however, differs remarkably. In 

 hirundo the outer webs of all the feathers are dusky-gray. In Forsteri the re- 

 verse is the case. The difference is even more marked than in the adults. 



There is little to be said with regard to the bibliography of this species. 

 In 1831 Swainson and Richardson describe it. calling it S. hirundo, but noticing 

 the discrepancies which exist in the tail and feet. In 1834, Nuttall seizes upon 

 these differences in a note under S. hirundo, and suggests for the species the 

 name of S. Forsteri, in the event of its proving distinct. The citation " S.. 

 hirundo, Rich., nee Linn.," is, I believe, the only synonym of this well-marked 

 specifcs, unless, indeed, it be necessary to refer to it the two preceding species. 



I append the detailed measurements of several specimens of this species, 

 which will serve to show within what limits it varies in size and proportions. 



Sterna hirundo Linn. 



Hirundo marina, Ray, Syn., p. 131. 



Sterna major, Brisson, Ornithologie, p. 113. 



Sterna hirundo, Linnaeus. Syst. Nat., i. 1766, 227; et auct. Fab. Fabric, et Rich. 



exceptis. 

 Hydrocecropis hirundo, Boie, Isis, 1844, p. 179. 

 ? Sterna fluviaiilis, Naumann, Isis, 1820, fide Temm. 

 Sterna marina, Eyton, Cat. Brit. Birds, 1836, p. 55. 

 Sterna Wilsoni, Bonaparte. Comp. List., 1838, p. 61, et auct. Amor, recent. = S. 



Mr undo ex Americd. 



" Great or Common Tern," Latham and English authors. ' Hirondelle-de- 

 1862.] 



