PICIB^S: WOODPECKERS. 485 



unbarred, the outer white, the central black. All the species of this genus are unfiueKti<juably 

 modified derivatives of one circuinpolar stock ; the American seem to have become completely 

 • difierentiated from the Asiatic and European, and further divergence seems to have perfectly 

 separated arcticiis from americanus ; but dorsalis and americanus are still linked together. 



Analysis of Species. 



Back uniform black nrclicns 443 



Back -with entirely interrupted lengthwise white stripe uiiirricaiius 444 



Back with nearly or quite uninterrupted lengthwise white stripe ilnrsalis 445 



443. P. arc'tious. (Lat. arcticus, arctic.) Black-backed Three-toed Woodpecker. Entire 

 upper parts glossy blue-black, with only a few white spots paired on tlie vviug-quills. Below, 

 white from bill to tail, the sides, flanks, and lining of wings barred with black. A slight or 

 conceale<l white post-ocular stripe (often wanting) and a side-stripe on head from across fore- 

 head to neck, cut off by black from the white of tlie under parts. Fimv middle tail-feathers 

 l)lack, tlie rest white, but the intermediate one usually touched with l)lack. ^ with a square 

 ycll(jw patch on crown, wanting in J. BiU and feet blackish -plumbeous ; iris brown. Length 

 9.00-10.00; extent 15.00-17.00; wing 5.00-5..50; tail 4.00; biU 1.25 or more. Northwestern 

 Am., S. in winter through New England and generally along the northern tier of U. S., in the 

 mountains of the West to about 39° in Nevada and California. Habits of ordinary Picus. 

 Eggs 0.92 X 0.72. 



444. P. america'nus. (Of America.) Ladder-backed Three-toed Woodpecker. Upper 

 parts black, the middle line white, more or less completely ban'ed across with black; the 

 general effect thus of a " ladder-back." All the primaries and secondaries with paired white 

 spots <.ir bars. Four middle tail-feathers black, others white, the intermediate one usually 

 touched with black. Below, white from bill to tail, the sides, flanks, and lining uf M-ings 

 black-barred. A white post-ocular striije to nape, and a larger white stripie from Lire to side 

 of neck. <J with a yellow square on crown, wanting in J ; in both, crown seldom uniform 

 black. Bill and feet blackish-plumbeous; iris brown. Smaller than the last ; length 8.00- 

 9.00; extent 14.00-16.00 ; wing 4.50-5.00 ; tail imder 4.00; bm 1.25 or less; whole foot 1.50. 

 Northern N. Am., S. to Massachusetts and along northern tier (jf States. 



445. P. a. dorsa'Us. (Lat. dorsalis, relating to dorsum, the back.) Pole-backed Three- 

 toed AVoodpeckek. In extreme case, the bade with an uninterrupted white lengthwise 

 stripe, producing the efi'ect of a " pole-back," as in P. mllosus for instance; this is produced by 

 such increase of white on the ends of the individual feathers that their black bases do not show 

 the subterminal black bars of P. hirswtus disappearing. Usually partly banded black and 

 white, and grading bar by bar into hirsuttis. The amount of spotting on the wings is about 

 as in Picas harrisi — on primaries and secondaries, not on coverts. Size of hirsuttis. Eocky 

 Mt. region, U. S., S. to New Me.vico. 



154. SPHYROPI'CXJS. (Gr. a-(/)Cpa, .s^/jMra, a hammer ; and Lat. ^ia«s.) Sap-sxtcking Wood- 

 peckers. BlQ about as long as head, not so stout and chisel-like as in the foregoing genera ; 

 pointed, with little bevelling at extreme end only, and lateral ridges running obliquely into the 

 commissure at about its middle ; culmen and gonys both a little curved ; nasal tufts moderate. 

 Wing pointed by 4th primary; 3d and 5th nearly as long; 2d between f.th and 7tli; spurious 

 1st very short. Taa-feathers long-acuminate. Outer hind toe little longer than outer front 

 one ; inner hind toe extremely short. Plumage highly variegated with yellow and red. Sexes 

 unlike. Tongue scarcely extensile : the tip obtuse, brushy ; hyoid bones short. Birds of this 

 remarkable genus feed much upon fruits, as well as insects, and also upon soft inner bark 

 (cambium) ; they injure fruit-trees by stripping off the bark, sometimes in large areas, instead 

 of simply boring holes. Of the several small species commonly called " sapsuokers," they alone 

 deserve the name. In declaring war against woodpeckers, the agriculturist will do well to 

 discriminate between this somewhat injurious and the highly beneficial species. 



