TABLE OF CONTENTS. x1 
Page. 
Key to the Species of Thalasseus......-....-2---- eee eee eee erence eee neee 467 
2. Thalasseus maximus (Boddaert).............2.2020eceeeceeeeeeeeeenee 467 
3. Thalasseus elegans (Gambel).................sees cece eee se ee eeeeeeee 472 
4, Thalasseus eurygnathus (Saunders)............0.02eeee cece ence e cence 474 
5. Thalasseus sandvicensis acuflavidus (Cabot).........0.sssseeeseeeeees 476 
Genus 3. Gelochelidon Brehm............2 00. cece ees c cece cece n een ceeceece 478 
6. Gelochelidon nilotica (Gmelin)...........2.....2- 2 eee cone cece eee e ence 479 
Genus 4. Sterna Linnwudeccisccccsesseveeeseccecesscaawatinenvaiceeecvexacae 485 
Key to the Species of Sterna... 22.0.2... 0.2. c cece cece eee e cence creer ee eenaes 486 
7, Sterna trudeaui Audubon.............. eee eee cece eee e cece ee ecesece 488 
8: Sterna forsterl Nuttall occwcc cc ovecsewssessssiseunpaecescmucewseccs 490 
9. Sterna hirundo Linnaeus. .... 2.22.2... eee eee cece eee eee e cece eens 493 
10. Sterna paradiseea Briinnich.............. 222-222 - eee cece eee eee eee 499 
11. Sterna dougalli Montagu...........- 2.2. cece eee cece eee cence ee eenes 505 
12. Sterna aleutica Baird............-...-.2.0-000- epolonayarciassanieacrenuraraiarateyela 510 
13. Sterna anztheta recognita Mathews..........-0-0-2ce cece eee eee e eens 512 
14. Sterna aneetheta nelsoni Ridgway...........--.e-e-ee cece eee cence 514 
15. Sterna fuscata fuscata Linneus........--.2-- 2s cece eee ee cece eee eee 514 
16. Sterna fuscata crissalis Lawrence..........-.220- 20sec eee eee cree eee 519 
Gentis'd:. Stermuls Boles ccd ssccsasecnmmnawacecmace eau aminmicersaresase-oiecincen 520 
Key to the American Species and Subspecies of Sternula.............-.----- 520 
17. Sternula antillarum antillarum (Lesson). .........-.-0---+-eeeeeeeee 521 
18. Sternula antillarum browni (Mearns)........ ipa aaticasiea caer bio mutate aiahe 525 
Genus 6. Hydrochelidon Boie...............002.cceceeceeeeeeeceeeeeeeeeees 526 
Key to the Species and Subspecies of Hydrochelidon....................2+-- 527 
19. Hydrochelidon leucopareia (Temminck). ............222-.022e eee ee eee 528 
20. Hydrochelidon nigra surinamensis (Gmelin)...............-.---+---- 532 
21. Hydrochelidon leucoptera (Temminck)............--.----+-- geenepsieaia 536 
Genus 7;. Phéetusa Waplers a... .csiccccc ccc ss cee nines vem mweiamiecicemmennci 540 
22. Phetusa chloripoda (Vieillot).....-..22.2- 0.220220 e eee cee cece eee 541 
Genus 8. Anous Stephens, . i.e ce cece ewes eaieieeaiased aise eieeide wanisciiee 544 
Key to the American Subspecies of Anous stolidus.......-..-..--.--2--220-- 545 
23. Anous stolidus stolidus (Linneus)..........---2---2--2-20--ee eens 546 
24, Anous stolidus ridgwayi Anthony.........-...2-.--------eee ee eee eee 550 
25. Anous stolidus galapagensis (Sharpe)....-.-.-.-2.2--2-0-see cece eens 551 
Genus 9. Megalopterus Boie...........2.---0-22-e eee ee eee cece eee eee e eee 552 
Key to the Species and Subspecies of Megalopterus.....-.-.-.------------+-- 553 
26. Megalopterus minutus atlanticus Mathews. ...........-.------------ 554 
27. Megalopterus minutus diamesus (Heller end Snodgrass). ...........-- 556 
Genus 10. Gygis Wagler. .. ssc: ssecessesccnetesd ee cceenecssseeeeneseenees 557 
Key to the Species of Gygis ....-.-. 2... 2.2. e cece cece cere reece eee eee nee 558 
28. Gygis alba candida (Gmelin)...........--.---2-+-e20-- sosrcisishaporxats 559 
Famity DARD; “THE GUUS 2205 .eeccncacanecsaaamciaseineesdesienesiece es 561. 
Key to the Genera of Laridee........-....2-02.0 cece nee e eee eee cence eee eenee 562 
Genus 1. Rissa Stephens...-...-..-.- 20.222 eee eee e eee cnet e eee e ence eee .-- 564 
Key to the Species and Subspecies of Rissa....--...-------+------eeee eee eee 565 
1. Rissa tridactyla tridactyla (Linneeus).............-2e eee eee eee eee eee 565 
2. Rissa tridactyla pollicaris Stejneger........-..------eeee eee e eee ee eee 571 
3. Rissa brevirostris (Bruch) .-.....--.-- 0. seen eee eee reece een e eee ceeeee 573 
Genus 2. Pagophila Kaup ........- RC PR er rer er eri 575 
4, Pagophila alba (Gunnerus)........-0.-. 20-0 seen eee eee eee eee e eens 576 
Genus 3. Tartid Dinnseuse 2.0 c.c ccc seaenaeneeee accuses ecemnseeeeeeues 580 
