100 



FACULTIES OF BIRDS, 



Teeth of the Blue Macaw (Ara amrawna), a, Upper mandible ; J, Lower 

 mandible : in section, to show the teeth ; c, Portion of ditto, showing the 

 teeth worn down by use. 



According to M. Geoffroy St. Hilaire, then, the 

 bill of a bird represents that sort of teeth which he 

 terms composite, of which the teeth of the elephant 

 furnish another example, and which consists of a 

 series of plates or dentary cones, each covered with a 

 pulpy plate or cone, and all re-united into one mass 

 by enamel or a cortical envelope. The only diffe- 

 rence of these consists in the nature of the sub- 

 stance oozing from the nucleus, and in the constant 

 absence of sockets and fangs. These interior cones 

 or plates are also distinguishable in the substance of 

 the bills of ducks, and are terminated in a more dis- 

 tinct manner in little plates or denticulations, all 

 around the edges of the bill. The latter differ from 

 those of the paroquet in being permanent in adult 

 birds. The divisions on the edges of the bill are 

 much deeper and more numerous in the shoveller 

 duck (Rhynchaspis clypeata, LEACH). These indeed 

 very much resemble the whalebone, or baleen, as it 

 has been called, of the whale*, and is intended, it 

 would appear, for a similar purpose, namely, to 



* Geoffroy St. Hilaire, Syst. Dentaire des Mamm, et des 

 Oiseaux, 8vo. Paris, 1824. 



