120 GENERAL OTtNITHOLDGY. 



KvrffiTj, hieme, same as Lat. cms), wliie.h in some birds, as loons, runs high up in front above 

 the knee-joint. Below, the tibia alone forms the ankle-j(iint, C, by articulating witli the next 

 l)one. For this purpose it ends in an enlarged trochlear (Gr. TpoxaXia), or puUey-lilce surface, 

 presenting a little forward as well as downward, above which, in many birds, tliere is a little 

 bony bridge beneath which tendons passing to the foot are confined. Tliis finishes the leg, 

 consisting of thigh, A B, and leg proper, B C, bringing u? to the ankle-joint at the heel, C. 



Now a bird's legs, unlike ours, are not separate from the body from the hip downward; 

 but, for a variable distance, are enclosed within the general integument of the body. The 

 freedom of the limb is greatest among the high perching birds, and especially the Raptores, 

 which use the feet like hands, and least among the lowest svi'immers. The range of variation, 

 from greatest freedom to most extensive enclosure of the limb, is from a little above B nearly to 

 C, as in the case of a loon, grebe, or penguin. In no bird is the knee, B, seen outside the 

 general contour of the plumage: it must be looked or felt fir among the feathers, and in most 

 prepared skins will not be found at all, the fenmr having been removed. It is a point of little 

 practical consequence, though bearing upon the generalization just made. The fii-st joint, or 

 bending of the limb, that appears beyond a bird's plumage is the heel, G ; and this is -what, 

 in loose popular parlance, is called "knee," upon the same erroneous notions that make people 

 call the wrist of a horse's fore-leg "knee." People also call a bird's cms or leg proper, B to C, 

 the "thigh," and disregard the true tbigb altogether. This confusion is inexcusable; any one, 

 even without the sliglitest anatomical liuowledge, can tell knee from heel at a glance, wbatever 

 tlieir respective positions relative to the body, /tdee is at junction of thigh and leg proper; 

 it always hends forward; /ieeHs at junction of leg with foot, and always bends backward. 

 This is as true of a bird, which is digittrp-ade, that is, walks on its toes with its heels in the 

 air, as it is of a man, who \s. plantigrade, that is, walks on the whole sole of the foot, with the 

 heel down to the ground. In a carver's language, the thigh is the "second joint" (from 

 beltiw) ; the leg is the "drumstick " ; the rest of a fowl's bind limb does not usually come to 

 table, having no flesh upon it. (See frfintispiece, "Di, Kn, Lg.) 



Before proceeding to the next segment of the limb, I must dwell upon the ankle-joint, 

 situated at tlie heel, — the point C, — corresponding to the carpal angle or bend of the wing, 

 C, in fig. 27. There we found, in adult birds, two small carpal bones, or bones of the wrist 

 proper; and noted the presence in the embryo of several other earpals (fig. 29), which early 

 fuse with the metacarpus. Just so in the ankle, there are in embryonic life several tarsal bones, 

 or bones of the tarsus (Lat. tarsus, the ankle) ; all of which, however, soon disappear, so that 

 there a];)pears to be no tarsus, or collection of little bones !)etween the tibia and tlie next 

 segment of the limb, the metatarsus. An upper tarsal b<ine, or series of tarsal bones, fuses 

 with the lower end of the tibia, making this leg-bone really a tiMo-tarsus ; and similarly, a 

 lower lione or set of bones fuses with the upper end of the metatarsus, making this bone a 

 tarso-metatarsus. So there are left no free bones in the ankle-joint, which thus appears to be 

 immediately between the leg-bone and the principal foot-bone; but which is nevertheless 

 really between two series of tarsal b(nies, the identity of which has been lost.^ 



1 Tlie exact homologues of a bird's vanishing tarsal bones are still questioiierl. Gegenbaur showed the so- 

 called epipli'ysis or shoe of bone at the foot of the tibia, and the similar cap of bone on the head of the principal 

 metatarsal bone, to be true tarsal elements. Morse went further, sliowing the tibial epiphysis, or upper tarsal bone 

 of Get;ent)aur to be really two bones, which he held to correspond with the tibiale and fibulare, or a^frnrialus and 

 ca/cfTHciim of mammals; these subsequently combining to form the single upper tarsal bone of Gegenbaur, and 

 finally becoming anchylosed with the tibia to form the bitrochlear condylar surface so cliaracteristic of the tibia ot 

 ytres. The distal tars.al ossicle he believed to be the nnitralc of reptiles. Wyman discovered the so-called " process oi 

 the astragalus " to have a distinct ossitication, and Morse interpreted it as the intermt'dium of reptiles. Later 

 views, however, :is of Huxley and Parker, limit the tibial epiphysis to the astragalus alone of mammals. If these 

 opinions be correct, other tarsal elements (more than one) .are to be looked for in the epiphysis of the metatarsi].^. 

 Whatever the final determination of these obscure jioints may be, it is certain that, as said in tbe text above, the 

 lower end of a bird's tibia and the uj>per end of a biril's metatarsus include true tarsal elements, just as the upper 



