BEAK OF BIEDS. 



21 



Java has 270 species of land birds, of which about 45 are peculiar, most of 

 them being from the mountains in the western part of the island. The re- 

 appearance in Java of several Burmese species (including Pavo mutieus) which 

 do not occur in the Malay peninsula south of Penang is very remarkable. 



Of Bali, so interesting as the southern outpost of the region, we only know 

 from Mr. Wallace that he saw there several birds highly characteristic of Javan 

 ornithology, and whether the island has any peculiar species nowhere appears 

 (Enc. Brit). 



THE BILL OR BEAK OF BIRDS. 



The bill or beak of birds consists of two parts, generally called the upper and 

 lower mandibles, but more properly maxilla and mandible. 



The externally visible part of each is an epidermic sheath of horny, or some- 

 times leathery, consistence, which covers the anterior bony prolongation of the 

 cranium in the one case (the premaxillary bone), and of the lower jaw in the 

 other (the dentary bone). 



In most birds the sheath (rhamphotheca) of each jaw is entire (as the Storks), 

 but in some (as the Petrels) it is " pieced," or divided into distinct parts by 

 various lines of slight connection. 



The different parts of the bill have received names useful for descriptive 

 purposes. Of these the following are the most important : — 



The whole length of the middle line of the upper surface, from the tip or 

 apex to where the feathers commence on the forehead, is called the culmen. 



The lateral sharp edge of the horny covering of either maxilla or mandible is 

 the tomium. 



The point at which the edges of the jaws meet behind is the commissure, or 

 angle of the mouth (sometimes called the gape). 



The mandible is composed of two lateral halves, called rami or branches, 

 separate behind, but united in front; the space between them where they are 

 separate is the inter-ramal space; the lower median edge of the mandible, from 

 the point at which the rami unite to the tip, is called the gonys. 



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Nat. Hist. Museum. D. cMororhyncha— Yellow-nosed Albatross, ^^^s^ 



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