24 The Anatomy of Birds 



to the water, growth of bone in the palatal region has converted it into a com- 

 pletely desmognathous cranium. 



Two other features remain to be considered in connection with the skull, the 

 hyoid, and those modifications of the nasal bones and narial openings termed by 

 Garrod holorhinal and schizorhinal. In the holorhinal type the openings are 



FIG. 19. Tongue and hyoid bones of various birds. (After Lucas.) 



a, hyoid of Pewee (Sayornis fuscus) ; b, hyoid of Cormorant (Phalacrocorax wile); c, hyoid of Muscovy Duck 

 (Cairina moscliala); d, hyoid of Hummingbird (Selasphorus rufus) ; e, hyoid of Flicker (Colaptes auralus). All figures 

 drawn to the same absolute scale, ch, ceratohyal; bh, basihyal; bb, basibranchial ; cb, ceratobranchial. 



more or less oval, the posterior border curved and lying in advance of the posterior 

 ends of the premaxillaries. In the schizorhinal type the openings are more or 

 less elongate, with the posterior border angular or slit-like and lying back of the 

 posterior ends of the premaxillaries. 



These features are, to some extent, valuable in classification, but by no means 

 of the importance at first ascribed to them by Garrod, being one of the many 

 emphatic warnings that birds may not be classified by any one set of characters, 

 but by the resultant of many. 



