128 GENERAL ORNITHOLOGY. 



as a core to the claw. The diifereuce in the lengths of the several phalanges, hke that of 

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

 perfectly upon an irregular object. The design and the principle are the same as seen in the 

 human hand, in which model instrument 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 front toes are inserted on the metatarsus on the same level, or so nearly in one 

 horizontal 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. But the hind toe, or hallux, as it is often 

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

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

 this digit varies, from the very bottom of the tarsus {metatarsus), where it is on a level with 

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

 the other toes, so that its whole length is on the ground, it is said to be incumbent. When 

 just so much raised that its tip only touches the ground, it is called insistent. When inserted 

 so high up that it does U(jt 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 inserted 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 of 

 aU insessorial (Lat. insedo, 1 sit upon) or perching birds to have the hind 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 

 CaprimulgidcB, perhaps also of Cyj)selid(B, and of Cathartidce. But among other Raptores 

 l>esides Cathartidce, especially certain owls {Striges), and in some of the pigeons (Colutnhida) , 

 the hind toe is not quite down, or is decidedly uplifted (as in Starnoenas, for example). It is 

 elevated in all oitr rasorial birds (Gallims); elevated in all our waders excepting the herons 

 and some of their allies (Herodiones) , though not very markedly so in the rail family {Rallidm). 

 It is elevated in all swimming birds, whether lobe-footed or completely or partly web-footed, 

 but in the totipalmate order (Stegnnopodes), where the hallux is lateral in position and 

 vN^ebbed with the inner toe, the elevation is slight. 'Now since, curiously enough, the only 

 ones of our insessorial genera (see above) that have the hind toe up, have also little webs 

 between the front toes — since some Raptores are our ouly other insessorial birds with any 

 ■such true webbing — since herons and some of their allies are our only birds with such 

 webbing that have the hallux down — the following rule is perhaps infallible for North 

 American birds : Consider the hind toe UP in any bird with any true webbing or lobing of the 

 front toes, excepting herons and some of their allies and some birds of prey. The converse 

 also holds almost as well ; for our only birds with fully cleft anterior toes and hind toe up, are 

 the rails and gallinules (Rallidcs), the black-bellied plover (SquatUrola helvetica), our only 

 four-toed plover, the turn-stone {Strepsilas interpres), the American woodcock (Philohela 

 minor), the European woodcock (Scolopax rusticula), Wilson's snipe (Gallinago tvilsoni), and 

 most of the sandpipers {Scolopaddce) . If the sense of this paragraph is taken in, the student 

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

 toe up or down. 



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

 of birds : in all insessorial birds, nearly all cursorial (Lat. cursor, a courser), and most natatorial 

 (Lat. natator, a swimmer) forms. Its length, claw included, may equal or surpass that of the 

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

 when incumbent ; when thus down on a level with the rest it also acquires its greatest mobiUty 



