62 KEY TO THE GENERA. 
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IV. [Tors 4,—3 IN Front, 1 BEHIND.] 
§. HIND TOE INSERTED ABOVE THE LEVEL OF THE REST (AND ALWAYS SHORTER THAN THE SHORTEST 
ANTERIOR TOE). (A) 
§. HIND TOE NOT INSERTED ABOVE THE LEVEL OF THE REST (AND generally but not always NOY SHORTER 
THAN THE SHORTEST ANTERIOR TOE). (B) 
A. (The hind toe elevated.) 
1. Feet TOTIPALMATE; (all 4 toes webbed ; hind toe semilateral and barely elevated.) (A) 
2. Feet PALMATE; (3 front toes completely webbed, hind toe well up, simple or lobed, free or connected by 
slight webbing with base only of inner toe.) (1) 
3. Feet LOBATE; (3 front toes (partly webbed, or not, and) CONSPICUOUSLY bordered with plain or Scare 
membranes ; hind toe free, and simple or lobed.) (C) 
4. Feet SEMIPALMATE; (2, or 3, front toes webbed at base only by small yet evident membrane; hind toe well 
up, simple.) (D) 
5. Feet SIMPLE; front toes with no evident membranes ; hind toe well up, simple. (B) 
(A) Tarsus feathered, partly; tail deeply forked; bill epignathous, . . . © 61a) ee) CLA CHYPE MENEAME 
—naked; bill>tail, hooked at tip, furnished with an enormous merrates . « « « PELECANUS 274 
—< tail; throat feathered; middle tail feathers filamentous, . . .. - PHAETHON 278 
—naked; tail pointed, soft; tomia subserrate, . . . . . . . SULA 273 
— rounded, stiff; bill paragnathous, . . .. . . PLOTUS 276 
—epignathous, .. . . . GRACULUS 275 
(B) Hind tee ecmewhat lateral, and joined by slight web to base only of inner toe, . . . . COLYMBUS 311 
— directly posterior, free, and simple or lobed. (h) 
(h) Bill—recuryed, depressed at base, subulate, extremely acute, . . . . . . . . RECURVIROSTRA 196 
—bent abruptly downward near its middle, and lamellate, ©. . . . . . » PHOENICOPTERUS 246 
—neither recurved, nor abruptly bent. (i) 
(i) Bill—hypognathous, corneous, cultrate, suleate, . . . - . - + « «+ «© «+ « « RHYNCHOPS 265 
— paragnathous, comeous, not lamellate; nostrils not tubular; tail not even. (k) 
— epignathous (or paragn. end tl. even), corneous, not lamellate; nostrils nod tubular. (1) 
—epignathous, corneous, not lamellate; nostrils tubular. (m) 
—paragnathous, mostly membranous, lamedlate, nostrils not tubular. (n) 
(x) Tail graduated, and middle feathers shorter than next pair. Plumage sombre brown . . . ANOUS 294 
—forked; toes almost semipalmate. Black, brown or ashy, and white, . . . |. HYDROCHELIDON 252 
—well webbed; feet not black; back pale; nocrest, . . . .. . . . . STERNA 291 
—blk.; wht. crescent on forehead (Sterna, 291, or) . HALIPLANA 293 
—no crescent; not crested; b. barely >trs., GELOCHELIDON 289 
— crested; b.much>trs., . THALASSEUS 290 
1) Bill with a sort of cere; middle tail feathers exserted; tarsus <3tel., . . . . . . . . BuPHAGUS 279 
—=3tel, .. . . . . STERCORARIUS 280 
—not cered; hind toe rudimentary, not bearing a perfect claw, . . ol as Rime @, 2s EIB SAGs 
— perfect; tail wedge-shaped; a dark collar round neck, - RHODOSTHETHIA 286 
— forked; bill black, tipped with yellow, . . ... . . . XEMA 287 
—reddish, not tipped with yellow, . . . CREAGRUS 288 
—even; tarsus black, rough; websincised, ... . PAGOPHILA 285 
—not black. Under plhimage — (1?) 
(1?) dark, head white, tail black, bill and feet reddish, . . . . BLASIPUS 282 
(12) white, head dark (if dark, head whitish), . . . CHRGCOCEPHALUS 283 
(12) white, head white (if dark, head not whitish), . . + . . . LARuS 281 
(m) Tarsus not <3t.; claws depressed, obtuce; tarsal scutella fused; webs with yellow, . OCEANITES 307 
—distinect; webs black, . . . . FREGETTA 8(8 
—compressed; tail cuneate; no white anywhere, .... . HALOCYPTENA 303 
2 —nearly even. Blk. or smoky brown, and white, PROCELLARIA 304 
—forked. Blk. or smoky brown, and white, . CYMOCHOREA 305 
—Not black and white, . . . . . OCEANODROMA 306 
(m) Trs. <3tel.; tail of 12 feathers; nasal tube obliquely truncate, septum thick, . . . . . PUFFINUS 310 
— vertically truncate, septumthin, . . . . PRIOFINUS 309 
—> 12 fthre.; plmg. conspicuously spotted, . . . . . . . =... =. - DAPTION 301 
—unspotted; tl. cuneate, . . . . . . AESTRELATA 362 
—not cuneate; 16-fthid, OSSIFRAGA 298 
—4-ithrd. b. << trs., FULMARUS 299 
—=trs., PRIOCELLA 300 
(n) Lamelle acute, like saw-teeth, retrorse; bill terete, black; trs.=}36., . = LOPHODYTES 272 
—not black; trs.>33t., . ... . . . MERGUS 271 
—simple; bill depressed toward end; lores naked. Adult entirely white, . . . . . CYGNUS 247 
— feathered; trs. in front—reticulate. (0) 
—scutellate. (p) 
(o) Trs. not>38tcl. Plumage partly lavender-colored, head white, throat black,. . . . . . PHILACTE 249 
—>3tel.; bill and legs not black. White or gray, bluish, speckled, ete., . . . . . . ANSER 28 
: — black; neck ell black: nostrils median, . ... . . . . BRANTA 250 
—not all black; nostrils subbasal,. . . DENDROCYGNA 251 
