ALCIDJE: AUKS. 797 



the end. Tareus much abbreviated, comparatively stout, about three-fourths as long as middle 

 toe aud claw. Middle aud outer toes nearly equal. Basal seniipahuatiou of toes more exten- 

 sive than in Podicipes. Lobe of hind toe moderate. 

 852. P. podi'cipes. (For podicipes, see above.) Pied-bllled Guebe. Dabchick. Dipper. 

 DiEUAPPEU. Waterwitch. Adult, breeding plumage : Bill light dull bluish, or bluish- 

 white, dusky ou 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. Si<les 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 uuifonnly 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 scuteUate. Tibio- 

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

 Colymhidce or Podidpedidce ; often curicjusly 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 ptilopaedic. Eggs few or 

 single, plain or variegated. The numerous species confined to the Northern Hemisphere. 



Birds of this family wiU be immediately recognized by the foregoing circumstances, taken 

 in connection with general pygopodous characters. Agreeing closely in essential respects, they 

 dift'er 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 homy 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 fonn 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 li. Ridgway in the case of our White Pelican, which drops the "centre- 

 board." In the Common Puffin, for example, no fewer than nine pieces of the bill fall of 



