32J= KEY AND UESVRIPTION 



outer web and tips of jirimaries blackish, and the rest of the 

 phimage white. In the breeding season, there is a black cap, 

 but during the rest of the year the head is streaked black and 

 white. This is much like the last species, but in all ages and 

 seasons, the royal tern can be distinguished by the inner Aveb of 

 the primaries which is Avhite, at least on the inner half. This 

 is a common, strong, and powerful tern of the southern coasts, 

 and is nearly as large as any gull ; so the student may distin- 

 guish the gulls from the terns by noting the difference in the 

 position of the heads of the species when in flight. The gull's 

 head is in line with the body, the tern's points toward the earth. 



Length, 19; wing, 14.] (14-15); tail, 7, forked, 3i ; tarsus, If; cul- 

 nien, 2i ; America, cliierty tropical ; breeding north to Virginia ; wander- 

 ing to Massacinisetts and the Great Lakes, and wintering from the Gulf 

 coast southward. 



4. Cabot's Tern (()7. S(<'nin sandvic4nsis aciijidvida). — A 

 southern, crested, pearl-gray-backed, white-bellied tern, with a 



large, yellow-tipped, bku-k 

 bill, and black feet. In the 

 breeding season, the whole 

 top of the head and crest 

 is black, but during the rest 

 Cab.t's Tera of the year the crown is 



white, somewhat spotted 

 witli black, and the crest black streaked with white. The 

 youiitj has the pearl-gray back spotted with blackish, the slaty- 

 gray tail short, and the bill nearly all black. (SandAvnch Tern.) 



Length, 15 ; wing, 12i ; tail. (>, forked over 2 ; tarsus, 1 ; culmen, 2\. 

 America, chiefly tropical ; breeding along the Gulf coast, and along the 

 Atlantic north to South Carolina ; wandering north to New England, and 

 wintering from Key West to Central America. 



5. Forster's Tern (09. Sth-)ta f()rsteri). — A medium-sized 

 tern, with wings and back pearl-gray, rump and all under parts 

 white, aiul bill blackish at tip and didl orange at base. The 

 tail is light colored, and the inner webs of the tail feathers are 

 always darker than the outer ones. In summer, the whole top 



