78 TERNS.

mostly or entirely white; 21 black space generally on the side of the head inelosing the eye . . . . . (i9. FURSTER’S TERN (1111.). b". Outer web of outer tail—feather darker than inner web; tarsus

over 70 . . . . . . . . 70. COMMON TEEN (1m. ). b9. Outer web of outer tail- feather darker than inner web; tarsus under 70 . . . . . . . . . . . 71. ARCTIC TEEN (Im.).

1?. Wing blackish, over 9 00. y a. Under parts blackish. . . . . . . . . 75. SoorY TERN (Im.).

6. Under parts white . . . . . . . . . 7G. anLEn TEnN (1111.). 4. Crown silvery gray ; lores black; rest of" plumuge sooty black. 79. NODDY. II. Wing over 1300. A. Wing 1500 or over; outer primary mostly gray. 64. CASPIAN TERN. B. Wing under 1500; inner half of inner web of first primary white. 65. ROYAL TEEN.

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F10. (H.—F‘irst primaries of adult Terms. seen from below. (a) Caspian Tern; (b) Royal Tern: to) Common Tern ; ((1) Arctic Tern; (e) Roseate Tern.

63. Gelochelidon nilotlca. Hasselq. GULL-EILLEIS TERN; MARSH TERN. Ad. in, summer.—Top of the head and nape black; back and wings pale pearl-gray; outer web of outer primaries silvery; tip and shaft part of the inner web darker; inner part of the inner web, except for a narrow mar-