«TERNS. 77

power of flight has deservedly won for them the name of Sea Swal- lows. They capture their prey of small fish by plunging into the water, frequently disappearing and swimming a few feet beneath the surface. They nest in colonies. The nest is usually on the ground. Generally it is simply a slight depression in the sand, shells, or pebbles of a beach, or in the near-by seaweed, moss, or grasses. Sometimes it is scantily lined with bits of grass, seaweed, moss, etc., but these are

frequently wanting. KEY TO THE SPECIES.

I. Wing under 1300. 1. Entire top of the head jet—black. A. Bill black, or mostly black. (1. Feet black or blackish.

a1. Under parts black or blackish a . . . . . 77. BLACK TEEN.

(1’. Under parts white; bill black . . . . 63. GULL-BILLED TERN.

(1'. Under parts white; bill black, broadly tipped with yellow. 67. CABor’s TEEN.

(2. Feet yellowish or orange. 61. Outer tail—feathers pure white; outer web of first primary black. 72. ROSEATE TERN.

6'. Inner web of outer tail—feather gray; outer web of first primary gray . . . . . . . . . 69. Fons'rEE’s TEEN. B Bill mostly or entirely yellowish reddish brownish or orange. a. Under parts tinged with grayish; outer web 0! outer tail-feather gray; inner web wh1te.

(11. Bill broadly tipped with blackish; tarsus generally over ‘70. 70. COMMON TEnN.

a“. Bill without a distinct black tip; tarsus generally under ‘70. 71. ARCTIC TEEN. 6. Under parts pure white; inner web of outer tail-feather gray; outer

web white. . . . . . . . . . . 69. FORsTER’s TEEN. 2. Forehead white; lores black; crown jet— b—lack. A. Wing under 8 00; back pearl— gray. . . . . . . 74. LEAST TERN.

B. Wing over 8-00; back grayish brown or blackish. a. Back grayish brown; a white stripe from the forehead over the eye. 76. BRIDLED TERN. 0. Back blackish; white of forehead not reaching over the eye. , 75. Soorv TERN. 3. Forehead or crown white or grayish, sometimes speckled with black; lores not entirely black. A. Wing pearl-gray. over 9'00. a. Outer tail-feather entirely pure white. a1. Bill over 1-75, tipped with yellowish . . . 67. CABor’s TEEN. a”. Bill under 1'75. without a yellow tip . 72. RosEA'rE TEEN (11m). (2. Outer tail-feather not pure white. bl. inner web of outer tail—feather darker than outer web; outer web