. On the natural history and classification of birds . terally, on the same principle, though much less de-veloped, as we have already explained in the instanceof the cuckow. This inclination of the exterior fore toetowards assuming a versatile structure, can only berightly seen in birds which are fresh; for in dried spe-cimens the three anterior toes appear all on the sameplane; but even then the claw of this subversatile toeis always more inclined inwards than those of the twoothers ; a proof that they are not employed to graspthe same side of the surface of an object. An examin-ation of the
. On the natural history and classification of birds . terally, on the same principle, though much less de-veloped, as we have already explained in the instanceof the cuckow. This inclination of the exterior fore toetowards assuming a versatile structure, can only berightly seen in birds which are fresh; for in dried spe-cimens the three anterior toes appear all on the sameplane; but even then the claw of this subversatile toeis always more inclined inwards than those of the twoothers ; a proof that they are not employed to graspthe same side of the surface of an object. An examin-ation of the American sparrow-hawk (Falco sparverius),{fig. 66. a) a bird we have so often instanced, will showthis fact. But it is among the owls that this peculiarityof structure is most apparent (b) : the three anterior toesin this family are more equal in length than in any of theFalconidce, or in the perchers; so that the foot bears a jHjjf \c~§ onty one>tnat m tne middie, is directed forwards; theother two being so inserted as to grasp in a lateral di-. great resemblance to that ofthe swifts ; both being Fis-sirostral types. The foot ofthe owls, nevertheless, differmaterially both from theswifts and the falcons; for itmaybe said that, of the threetoes opposite to the hallux, 128 ON THE CLASSIFICATION OP BIRDS. rection: by this particular structure the bird couldbring the tips of all the four claws to touch each other,when grasping a small round substance, a faculty whichno other birds, from the different position of their toes,can possibly possess. The annexed sketch (fig. 66. b) ofthe foot of the little horned owl, or Scops, will illustratethis singular conformation of foot, which is altogetherpeculiar to such birds of the rapacious order as prey uponliving animals. The vultures, who do not seize theirfood by their talons, have no occasion for such a foot,and their toes are consequently placed in the ordinarydirection. CHAP. IV. THE SAME SUBJECT CONTINUED. ON THE DIFFERENT MODIF
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