732 
SYSTEM A TIC SYN OP SIS. — L ONGIFENNES. 
306. PHAETHON. (Gr. ^aW<ov, Phaethon, son of the sun.) Tropic Birds. Character as above. 
762. P. aethe'reus. (Lat. cethereus, pertaining to the upper air.) Red-billed Tropic Bird, 
Bill red ; tarsi and part of toes light colored ; rest of toes black. Plumage pure white, on 
nearly all the upper parts finely barred with black ; black markings on sides under wings ; a 
transocular fascia, outer webs and part of inner webs of most of the primaries, most of several 
inner secondaries, and most of the shafts of the tail-feathers, black, the shafts of the long middle 
pair, however, white in most of their extent. Length about 36.00 inches, including the long 
tail-feathers; without these, about 18.00; wing 12.00; long middle tail-feathers up to 18.00; 
tarsus 1.00 ; middle toe and claw 1.75 ; bill 2.50 along culmen, nearly 1.00 deep at base. Trop- 
ical and subtropical America, accidental in N. Am. ; said to have straggled to Newfoundland 
in one instance {Freke, Pr. Roy. Soc. Dublin, 1879). 
763. P. flaviros'tris. (Lat. fiavirostris, yellow-billed.) Yellow-billed Tropic Bird. Bill 
and tarsi yellow ; toes black. Plumage white, tinged with salmon or rosy on the under parts 
and long tail-feathers; lacking the barring with black of the last species, but with definite 
black areas — a transocular fascia, an oblique band on lesser wing-coverts and thence on scap- 
ulars and inner secondaries, shaft-stripes on outer five or six primaries, stripes on the flanks, 
and most of the shafts of the tail-feathers, including the middle pair. Smaller than the last; 
dcA^elopment of middle tail-feathers about the same; wing 11.00; bill notably smaller, only 
about 2.00 along culmen and 0.75 deep at base. This is the species figured by Audubon (8vo, 
pi. 427) under the wrong name of P. (Ethereus, which belongs to the foregoing. Tropical and 
subtropical America, rare or casual in the U. S., as on the Gulf coast. Has strayed to Western 
New York in one instance {Coues, Bull. Nutt. Club, v, 1880, p. G3). 
XII. Order LONG-IFENNEB : Long- winged Swimmers. 
Long -ivinged Natatores with open nostrils and small free or no hind toe. — Wings long, 
pointed, reaching when closed beyond the base, in many cases beyond the end, of the tail, which 
is usually lengthened and of less than 20 rectrices (oftenest 12). Legs more or less perfectly 
beneath centre of equilibrium when the body is in the horizontal position ; the crura more nearly 
free from the body than in other Natatores, if not completely external. Anterior toes palmate ; 
hallux never united with the inner toe, highly elevated, directly posterior, very small, rudi- 
mentary, or absent; tibiae naked below. Bill of variable form, but never extensively membra- 
nous nor lamellate, the covering horny throughout, sometimes discontinuous. Nostrils variable, 
but never abortive. No gular pouch. Altricial. 
This order, which may be recognized among web-footed birds by the foregoing external 
characters, is less substantially put together than either of the two preceding, — not that its 
components are not sufficiently related to each other, but because the essential points of structure 
are shared to a considerable extent by other groups. Thus the osteological resemblances of 
longipennine birds with loons, auks, and plover, are quite close, while the digestive system 
agrees in general characters with that of other fish-eating birds. In some of the lower mem- 
bers <»f the order, the tibia develops an apophysis, as in the loons ; while even in external 
characters, one genus at least (Halodroma) resembles the Alcidce. It is not certain that the 
order must not be broken up, or rather enlarged and diff"erently defined, to include some of the 
genera now ranged under Pygopodes. 
The palate has the schizognathous structure; '4he maxillo-palatines are usually lamellar 
and concavo-convex, but in the Procellariidm they become tumid and spongy " {Huxleg) ; 
basypterygoid processes may be wanting, but they are certainly present in many cases. The 
nasal bones are schizorhinai in Laridce, holorhinal in Procellariidce. There is apparently one 
pair of syringeal muscles throughout the order. The oesophagus is capacious and distensible ; 
there is no special crop ; the proventiculus is a bulging of the gullet ; the gizzard is small and 
