424 



NATURAL HISTORY OF BIRDS. 



mxp- 



clew to the peculiarities of the present family. The special use of the bill as a 

 hammer prevented its specialization in the same direction as in the aegithognathous 

 birds. 



Parker has briefly stated the chief saurognathous character to be " the want of 

 fusion of the parts of the palate at the mid line." This is especially the case with the 

 vomer, the two halves of which remain separate even in the adult state. They will 

 be seen as two thin styles along the inner margins of the palatines. The abortive 

 development of the maxillo-palatines is also very notable. Another feature is the 

 feeble development of the posterior part of the palatines, the external posterior angle 

 being usually absent. These peculiar- 

 ities 'are well shown in Fig. 212 A 

 and B, which, besides, demonstrates 

 the great general resemblance of the 

 woodpecker's palate and that of the 

 wryneck. 



There are other features in the 

 organization of the woodpecker which 

 indicate an approach to the Passeres 

 besides the palate, for, as we have 

 already remarked, the manubrial pro- 

 cess of the breastbone is bifurcate, and 

 the pterylosis is quite ' oscinine,' the 

 wing-coverts being small and few. 

 Another character of the wing, which 

 is isomorphic with the corresponding 

 one in the more specialized Passeres, 

 is the reduction in size of the first (or, 

 as would be more correct to say, the 

 tenth) primary. 



It would take more space than has 

 been allotted to the present family were we to describe in detail all the structural 

 peculiarities of the group, and, consequently, we are forced to content ourselves with 

 mentioning the curious machinery of the tongue. 



The woodpecker's tongue consists of the same bones as in most other birds, 

 except that the urohyal is entirely absent. The ceratohyals are only slightly devel- 

 oped, and early fused together. On the other hand, the basihyal and both pieces of 

 the horns (thyrohyals) are unusually slender and extremely elongated, often so long 

 that their ends reach forward over the top of the skull nearly to the tip of the bill, in 

 which case the whole apparatus slides forward in the sheath encasing the bones and 

 their muscles, when the tongue is thrust forward; or the ends of the hoi-ns are fastened 

 to the upper side of the skull, and their curvature hangs down along the sides of the 

 neck, as seen in the diagrams, Fig. 213 A and B. The extensor muscles which are 

 attached to the concave curvature of the horns and to the mandible, when contracted, 

 force the tongue forward a distance corresponding to the flattening of the loop of 

 the horns. By this means the cylindrical and worm-like tongue, which at the end is 

 provided with a pointed horny tip and barbed with sharp bristles, can be shot out far 

 beyond the tip of the bill, its flexibility enabling it to penetrate the winding tunnels 

 of the boring insects or the corridors of the industrious ants, on which most wood- 



FIG. 212. Palate of (A) Dryobates and (B) Jimx ; mxp, max- 

 illo-palatines ; pi, palatines ; pt, pterygoids ; v, vomer. 



