128 GENEBAL ORNITHOLOGY. 



as a core to the claw. The diii'ei-eiice iu the lengths of the several plialauges, hke that ot 

 the digits themselves, makes the toes mure efficient in grasping, since they thereby clasp mure 

 perfectly upon an h-regular object. The design and the principle are the same as seen in the 

 human hand, iu which model instrumeut the digits and their joints are all of different lengths. 



The Position of the Digits, other than in respect to their direction, is important. In 

 all birds the i'ruut toes are inserted on the metatarsus on the same level, or so nearly in (jne - 

 liorizontal plane that the difference is not notable. The same may be said of the hind toes ' 

 when they are a pair, as in zygodactyle birds. l>ut the hind toe, or hallux, as it is often ' 

 called, when present and single, varies remarkably in position with reference to the front toes ; 

 and this matter requires special notice, as it is important in classification. The insertion of 

 tliis digit varies, from the very bottom of the tarsus (metatarsus), where it is on a level witli 

 tlie front toes, to some distance up the bone. When the hallux is flush with the bases of 

 the (.ither toes, so that its whole length is un the ground, it is said to be incumbent. When 

 just so much raised that its tip oidy touches the grcjuud, it is called insistent. When iuserted 

 so high up that it does not reach the ground, it is termed remote (amotus) or elevated. 

 But as the precise position varies insensibly, so that the foregoing distinctions are not readily 

 perceived, it is practically best to recognize only two of these three conditions, saying simply 

 " hind toe elevated," when it is iuserted fairly above the rest, and " hind toe not elevated,'" 

 when its insertion is flush with that uf the other toes. In round terms : it is characteristic iif 

 all iiisessorial (Lat. insedo, I sit upon) or perching birds to have the liind toe down ; of all 

 other birds to have it UP (when present). The exceptions to the first of these statements are 

 extremely rare ; among North American birds they are chiefly furnished by certain genera of 

 Caprimulyidm, perhaps also of Cyxiselidcc, and of Catliartidce. But among other Maptores 

 besides Cathartida, especially certain owls (Stric/es), and in some of the pigeons (Coluvihida:), 

 the hind tue is not quite down, or is decidedly uplifted (as iu Starncenas, for exainple). It is 

 elevated in all our rasurial birds (Gallina;); elevated in all our waders excepting the herons 

 aiul some of tlunr allies (Herodiones) , though nut very markedly so in tlie rail family (Sallidfc). 

 It is elevated iu all swimming birds, whether lobe-footed <jr completely or partly web-fijoted, 

 but iu tlie tutipalmate order (Stef/aiiopodes), where the hallux is lateial in positicjn and 

 webbed vpith the inner tue, the elevation is slight. Now since, curi(.iusly euijugh, the only 

 <pnes uf our inscssorial genera (see above) that have the hind toe up, have also little welis 

 between the fruut toes — since some Bajjtures are uur only other iusessorial birds with any 

 such true webbing — since herons and sume uf their allies are our only birds with such 

 webbine; that have the hallux down — the follcjwing rule is perhaps infallible fur North 

 American lurds : Consider tlie hind toe vv in aynj bird with any true u-ebhinrj or lohing of the 

 front toes, excepting lierons and some <d' their allies ami some birds uf prey. The converse 

 also holds almost as well ; fur uur only birds with fully cleft anterior toes aud hind toe up, are 

 the rails and gallinules (lialUda'), the black-bellied plover (Sqiiafarola heli-etica), our only 

 fuur-tued ])luver, the turn-stone (Strepsilas intejyres), the American woodcock (Philohelu 

 mi'iior), the European woodcock (ScolojMtx nisticula.), Wilson's snipe (Gallinago wilsoni), and 

 must uf the sandpipers (iScoZopaciiia;). If tlie sense uf this paragraph is taken in, the student 

 who wishes tu use my artificial "key" will selduni be puzzled to know whether tu take the 

 toe up or down. 



The Hallux has other Notable Characters. — It is free and simple, in the vast majority 

 of birds ; in all inscssorial birds, nearly all cursorial (Lat. cursor, a cuurser), and must natatorial 

 (Lat. natator, a swimmer) furms. Its length, claw included, may eipuil ur surpass that of the 

 longest anterior tue ; and generally exceeds that of one or two of these. It is never so long as 

 ^\•llen incunihenl ; when thus down on a level with thi' rest it also acquires its greatest mobility 



