With the Woodpeckers we commence a series of bird-families sometimes combined under the general name of Picariae, but exhibiting such complicated relations with each other and with other groups of birds that their classification is by no means finally settled. In the present work it appears best to leave them in a number of small orders, each frequently consisting, as in the present instance, of a single family.
The Woodpeckers were formerly associated under the name Scansores with Barbets, Cuckoos, Parrots, and other birds having two hind and two fore toes, the fourth digit being directed backwards as well as the first or hallux. But the Parrots have long been known to differ from the others widely in structure, and were classed apart by Blyth in his Catalogue in 1849. Huxley, in his important paper ' On the Classification of Birds' (P. Z. S. 1867, pp. 448, 467), distinguished the Woodpeckers as a group called Celeomorphae, equal in rank to the Accipitrine birds or the Parrots, and the distinction was emphasized by Kitchen Parker, who separated Woodpeckers and Wrynecks as Saurognathae, on account of what he regarded as the reptilian characters presented by the bones of the palate. The view that "Woodpeckers and "Wrynecks form a separate group has been accepted by many recent writers, notably by Sundevall *, Sclater , Newton Sharpe §, and Gadow , though not by Garrod, by Furbringer **, nor by Seebohm The following are the principal characters :—
Vomer represented by several distinct paired lateral rods; maxillo-palatines small, widely distant from each other (fig. 9).
* Tentamen,' p. 72. 'Ibis,' 1880, pp. 350, 402.
* Article " Ornithology," Encyclopaedia Brit. p. 47.
' Review of Recent Attempts to Classify Birds,' p. 84. (The Neotropical Buccones and Galbulae are here associated.)
Bronn, Klassen u. Ordn. des Thier-Reichs, vi, 4, p. 301.
P. Z. S. 1878, p. 935. ' Untersuchungen,' ii, p. 1392.
' Classification of Birds,' p. 6; Supplement, p. 23.