H4-4 Bibliographical Notices. 



the air is allowed to escape from the pouch, but occasionally they 

 might be seen riving wrth it partly inflated.'* 



There is a point concerning this pouch of very great interest. It 

 is a secondary sexual character, developed during the breeding- 

 season, but so far we have no information concerning its nature or 

 the mechanism by which it is inflated and deflated. From an ex- 

 amination of spirit-specimens we believe that it will be found to be 

 nothing more than a widening of the oesophagus, filled through the 

 anterior nares, and held inflated by occlusion of the oesophagus by 

 means of a sphincter at the back of the mouth. 



One of the commonest mammals of the island is Mus Maclearii, 

 " It occurred in swarms. During the day nothing is to be seen of 

 it, but soon after sunset numbers may be seen running about in all 

 directions, and the whole forest is filled with its peculiar querulous 



squeaking and the noise of frequent fights As may be 



imagined, they are a great nuisance, entering the tents or shelters, 

 running over the sleepers, and upsetting everything in their search 

 for food. They seem to eat anything, and destroy any boots or skins 

 incautiously left within their reach." 



" One of the chief objects of the expedition to Christmas Island 

 was to find out whether its structure would throw any light upon 

 the vexed question of the nature of the foundation of atolls." 



This exceedingly difficult question is most ably and lucidly handled 

 in the concluding part of this volume. 



The occurrence in an oceanic island of thick beds of lower and 

 middle Tertiary limestone is a point of extreme interest and import- 

 ance, and the demonstration of this fact forms one of the many 

 important results obtained by Mr. Andrews. " Perhaps the most 

 remarkable of the rocks of Christmas Island are the thick deposits 

 of nearly pure phosphate of lime which cap several of the higher 

 hills. This substance is probably derived from ancient (? Pliocene) 

 guano-beds formed on the low islets which existed before the first 

 elevation of the island, and is the insoluble residue of beds of lime- 

 stone altered by this guano." 



Space forbids that we should extend this notice further ; enough, 

 it is hoped, has been said to show how admirably this work has been 

 carried out and how fruitful have been its results. 



We entirely agree with Sir John Murray, who, in his Introductory 

 Note, says, " It will, I think, be admitted that in the present 

 elaborate report we have the best account of a true oceanic island 

 that has ever been published." 



The illustrations, which are numerous, are, on the whole, very 

 good. The text-figures, however, and one or two of the plates are 

 about as badl) reproduced as could well be. W, P. Ptcraft. 



