THE NICOBAR PIGEON. 



523 



I may add that the Blrgus is partial to other kinds of fruits bo- 

 side cocoa-nuts. Different writers mention candle-nuts, nutmegs, 

 figs, and other rich and oily nuts and fruits. In some islands it 

 would seem that the Pandanus fruit is its only diet; and for break- 

 ing open these tough fruits, its heavy claws are well adapted, though 

 from personal experience, I should lemark that the crab would have 

 its strength and ingenuity taxed almost as much as in the case of 

 the cocoa-nut. 



Cartilaginous 

 body 



Jiliiscular 

 wall 



Gizzard-cavity 



The handsome ground-pigeon, known as the Nicobar })igeon 

 {Geopliilus iiicoharicus), is commonly observed in the wooded islets 

 < n the coral reefs of the Solomon Group. As I have remarked on 

 page 293, this bird is probably instrumental in transporting from 

 one locality to another the small hard seeds and fruits which the 

 common fruit-pigeon (Carpophaga) refuses. That it is able to crack 

 such hard seeds as those of the leguminous plant Adenanthera pav- 

 onina^ is shown by the fact that I have found these seeds cracked 

 in the cavity of the gizzard, which is in its structure and mechanism 

 a veritable pair of nutcrackers. In this bird the muscular stomach or 

 gizzard is of a surprising thickness, and is provided with a very 

 singular mechanical contrivance to assist its crushing power. As 

 shown in the accompanying diagram, it is composed of two muscular 

 lialves, each having a maximum thickness of five-eiohths of an inch 

 and united with each other in front and behind by a stout dis- 

 tensible membrane, which is the proper wall of the organ. Developed 

 in the horny epithelial lining membrane there are two cartilaginous 

 bodies of hemispherical shape, one in each muscular segment of the 

 gizzard, which measure about one-third of an inch in thickness and 



^ The Kuara tree of India, of whose hard seeds necklaces are made. 



