ALClDyE: ACrKS, MURRES, ETC. 1059 



DiVEDAPPER. Water-witch. Hell-diver. Adult J ? , breeding plumage : Bill light 

 dull bluish, or bluish-white, dusky on ridge or at tip, encircled with a broad black band. Iris 

 brown and white; eyelids white. Feet greenish-black outside, leaden-gray inside. Frontal 

 and coronal bristles black. Crown, occiput, and neck behind, grayish-black, the feathers with 

 slightly lighter edges ; sides of head and neck brownish-gray ; a broad black throat-patch, 

 extending on sides of lower mandible. Upper parts brownish-black, the feathers with scarcely 

 lighter edges. Primaries and secondaries chocolate-brown, the latter frequently with a white 

 area on inner webs. Under parts ashy, washed with silvery, thickly mottled with dusky; 

 these dark spots most numerous and evident on the sides ; lower belly nearly uniformly dusky. 

 Winter adults : Bill light dull yellowish, without a dark band, more or less dusky on the ridge. 

 No gular patch; throat whitish. Crown and occiput dusky brown; upper parts with more 

 evident pale edgings of the feathers than in summer. Neck, breast, and sides light brown, 

 darker behind, wliere more or less conspicuously mottled with dusky ; lower belly grayish ; 

 under parts otherwise pure silky-white, immaculate. Young: White of throat invaded by 

 brownish streaks; head streaked with white. Downy young: Blackish above, with 4 whitish 

 stripes ; head and neck streaked with black and white, and spotted with rufous. Length about 

 13.00; extent 24.00; wing 4.50-5.00; culmen 0.85; gape 1.20; height of bill at nostrils 0.40; 

 ■width 0.25; tarsus 1.50; middle toe and claw 2.15. Varies greatly in size: Length 12.00- 

 15.00, etc. Inhabits the greater part of Soutli and Central America and all temperate North 

 America; tlie most abundant Grebe in the eastern U. S. at any season, breeding nearly 

 throughout its range. Eggs 4-6 or more, 1.70 X 0.95. 



Suborder ALC^ : Auks. 

 The characters of this suborder are the same as those of its single family, as follows : 



Family ALCIDJE : Auks, Murres, etc. 



Feet palmate, three-toed (hallux wanting). Tarsi reticulate or partly scutellate. Tibio- 

 tarsal joint naked. Claws ordinary. Bill of wholly indeterminate shape, often much as in 

 Gaviidce or Podicipedidee, often curiously shaped, with various ridges, furrows, or horny pro- 

 tuberances, which latter are deciduous. Tail })erfect, though short, of 12-10 feathers (rarely 

 18 in one species). Lores completely feathered. Nostrils wholly variable in shape and posi- 

 tion, naked or feathered. Coloration variable; head often with long curly crests. No tibial 

 apophysis. Carotids double (single In Alle). Coeca present; accessory semitendiuosus absent ; 

 oil-gland tufted. Palatal structure schizognathous ; nasal schizorhinal. Skull with marked 

 supraorbital and temporal fossfc ; lacryinals fused; vomer bifid beliind ; basiptorveoids unde- 

 veloped; maxilliii)alatines laminate; sternum very long, with its median backward projection 

 beyond the lateral processes. Nature altricial and ptilopaedic, the young being nidicolous, not 

 nidifugous like those of Loons and Grebes. Eggs few or single, plain or varieiiated. The 

 numerous species confined to the Northern Hemisphere. 



Birds of this fLimily will be immediately recognized by the foregoing, in connection with 

 general pygopodous characters. Agreeing clo.seIy in essential respects, they differ amonir them- 

 selves to a remarkable degree in the form of the bill, with every genus and almost every species ; 

 this organ frequently assuming an odd shape, developing horny processes, showing various 

 ridi,'es and furrows, or being brilliantly colored. It is the rule that any soft part that may l)e 

 observed on the bill will finally become liard, or form an outgrowth, or both ; and such pro- 

 cesses, in some cases at least, are temnf)rary, appearing only during tlie breedinj; season. 



The last sentence, reprinted as it stands in the original edition of tiio Key (1872). Iiints 

 at the extraordinary clianges undergone by the bill in .several genera of AIcid>f, so ablv elnci- 



