ALCID^: AUKS. 
797 
the end. Tarsus much ahbreviated, comparatively stout, about three-fourths as long as middle 
toe and claw. Middle and outer toes nearly equal. Basal semipahnatiou of toes more exten- 
sive than in Podicijjes. Lobe of hind toe moderate. 
852. P. podi'cipes. (For podicipes, see above.) Pied-billed Grebe. Dabciiick. Dipper. 
DiEDAPPER. Waterwitch. Adult, 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 witli 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 the inner 
webs. Under parts ashy, washed over with silvery-gray, thickly mottled with dusky } these 
dark spots most numerous and evident on the sides. Lower belly nearly uniformly dusky. 
Winter plumage : Bill light dull yellowish, without a dark band, more or less dusky on the 
ridge. No gular patch. 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 
posteriorly, where more or less conspicuously mottled with dusky. Under parts otherwise pure 
silky- white, immaculate; lower belly grayish. Young-of-the-year : White gular patch in- 
vaded by streaks of the brownish of the head, and the latter much streaked with white. 
Dimensions: length about 13.00; extent 24.00; wing about 5.00; bill along culmen 0.75 ; 
along gape 1.20 ; height at nostrils 0.40 ; width 0.25 ; tarsus 1.50 ; middle toe and claw 2.15. 
Varies greatly in size. Inhabits the greater part of S. and C. Am. and all temperate N. Am. ; 
the most abundant species of the family in Eastern U. S. 
63. Family ALCID^: Auks. 
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 
Colymhidce or Podicipedidm ; often curiously shaped, with various ridges, furrows, or horny 
protuberances. Tail perfect, of few feathers. Lores completely feathered. Nostrils wholly 
variable in shape and position, naked or feathered. Legs very variable. Coloration vari- 
able ; head often with long curly crests. No tibial apophysis. Usually (always ?) an anconal 
sesamoid, sometimes double. Carotids usually double (single in Alle). Coeca coli pres- 
ent; ambiens muscle present, accessory semitendinosus absent; oil-gland tufted. Palatal 
structure schizognathous ; nasal schizorhinal. Nature altricial and ptiloptedic. Eggs few or 
single, plain or variegated. The numerous species confined to the Northern Hemisphere. 
Birds of this family M^ill be immediately recognized by the foregoing circumstances, taken 
in connection with general pygopodous characters. Agreeing closely in essential respects, they 
differ among themselves 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 pro- 
cesses, showing various ridges and furrows, or being brilliantly colored. It is the rule that 
any soft part that may be observed on the bill will finally become hard, or form an outgrowth, 
or both ; and such processes, in some cases at least, are temporary, appearing only during the 
breeding season. 
The last sentence, reprinted as it stands in the original edition of the Key (1872) hints at 
the extraordinary changes undergone by the bill in several genera of Alcidce, so ably elucidated 
in 1877 and 1879 by L. Bureau, who showed that in many species parts of the horny covering 
of the bill are regularly shed or moulted, in a manner analogous to the casting of deer's antlers, 
quite as shown by R. Ridgway in the case of our White Pelican, which drops the centre- 
board." In the Common Puffin, for example, no fewer than nijie pieces of the bill fall ofl 
