602 LESTRIDINJE — JAEGERS. 



The four toes have all the normal number of segments : 2, 3, 4, 5. They present 

 nothing of special interest, being of the ordinary size and shape. The hallux, and its 

 accessory metatarsal bone, may, however, be here described. It does not differ appre- 

 ciably throughout the family, except in the genus Missa of Larince, for the characters 

 of which, see under the head of the genus. 



Were it not for analogy, the o« metatarsale accesaorium might bo considered as a pha- 

 langeal rather than metatarsal stKrij(!Dt. It is nearly or quite as long as the first true 

 phalangeal bone. It is obliquely )J;i,tteiied, and somewhat twisted upon itself, tapering 

 to a'thin, rather acute, apex. Its distal extremity is broadened and oval, bearing a 

 slightly convex articulating surface, which is coapt.atcd with that of the first phalanx. 

 There is no eminence or depression of any consequence for its attachment with the 

 metatarsus ; it is only loosely connected by ligaments, and enjoys all the freedom of 

 motion which the hallux itself possess. Its essentially metatarsal character is nev- 

 ertheless demonstrated by its irregular and peculiar shape ; by the formation of its two 

 extremities ; and by the want of ajjroper articulation (capsulated and with a synovial 

 membrane) with the metatarsus. 



This bone in the Lestridinw differs from that of the other subfamilies in being shorter, 

 stouter, with a broader metatarsal extremity, and having a constriction about its 

 middle. 



The proximal phalangeal segment is a very short, stoat, straight bone, irregularly 

 cylindrical, with slightly enlarged extremities. These have subcircular articulating 

 facets, the proximal concave, the distal convex. The distal segment is merely a mi- 

 nute, irregularly shaped, osseous nodule, supporting the claw. 



Subfamily Lesteidin^. 

 DiAG. LAniD.E rostra ccrd instructo, rectridJma mediia elongatis, unguibus validiaaimw. 



Ch. Tip of the upper mandible overhanging that of the lower. Covering of upper 

 mandible not continuous, the basal half being furnished with a corneous cere, beneath 

 the edges of which the nostrils open. Culmen at first about straight, then rapidly con- 

 vex. Commissure slightly sinuate, declinato-convex on the terminal portion. Gonys 

 short, about straight. Rami widely divaricating, their outline about straight. Kmi- 

 nentia symphysis well marked. Nostrils lateral, pervious, somewhat club-shaped, being 

 widest at their distal extremity. Wings long, strong, pointed ; the primaries broad 

 and rigid, more or less rounded at the tips. Tail square, or nearly so, the centra! feath- 

 ers projecting to a greater or less distance beyond the others ; either rounded at their 

 tips, or attenuated and filiform. Legs decidedly ambulatorial, placed well forward, 

 supporting the Ijody in a horizontal posture. Tibiaj denuded of feathers on the lower 

 third. Tarsi rather stout, anteriorly transversely reticulated, posteriorly and laterally 

 reticulated, the plates more or less elevated and acutely pointed. Proportions of toes, 

 and their segments, as in other Laridce. Webs broad and full, their margins rounded, 

 not excised. Claws large, strong, curved and acute. Of moderate and large size. The 

 body fnll, the general organization strong and powerful. The changes of plumage in 

 most of the species, with age and season, very great. 



The anatomical characters of this subfamily are fully given under one of its most 

 common and tyiiical species, the Stercorarius pomatorhinus. 



5. Analytical table of the subgenera and species of North American Lestridima. 



I. Staturfl, maximns, et form^robustissimus; pedibus et rostro validis ; 

 tarso medio digito com ungue breviore ; caud4 brevi, rectricibus 



mediis latis, vix nltih ca:teras porrectis JBuphagus. 



a. Rostri longit. 2.00 poll, et ultra.; altitude 0.75 ; ab oris angnlo 



ad apicem 3.00 B.skua. 



n. Staturd minores, et forml graciliores ; pedibus et rostro gracili- 

 oribus ; tarso medio digito cum ungue non breviore ; caudJ, elon- 

 gate, rectricibus mediis valde ultra CEsteras porrectis Stercorarius. 



a. Tarsis posticfe asperrimis ; rectricibus mediis latis in apices 



ipsas, flexibilibus, c^eterLs 4 jjollices longioribus 8. pomatorhinus. 



b. Tarsis posticb subasperis ; rectricibus mediis acnminatis, ri- 



gidis, ejeteris 4 pollices longioribus S. parasiticus. 



c. Tarsis postice subasperis ; rectricibus mediis longissimis, 



flexibilibus, ca;teris S ad 10 poUices longioribus S. buffoni. 



