Note 254 — Chapter VIII · CUCKOOS—HONEY GUIDES—PLAINTAIN-EATERS—WOODPECKERS—TOUCANS—BARBETS.

Compare Fig. 1, ch.; this bone usually exists in a paired condition, but in Woodpeckers and some other birds it appears single by the confluence of its members. In many birds the “basi-hyal” is succeeded by the “uro-hyal” (Fig. 1, b. br.), a bone altogether absent whenever the tongue is capable of extraordinary protrusion.