IV INTRODUCTION. 



the habitat, and in general the collection from whence 

 the specimen has been purchased, or procured in ex- 

 change, is also marked; as it often gives some authenti- 

 city to its history. 



In the adoption of generic and specific names, it has 

 been thought right to use, wherever it was possible, that 

 which was first applied to the species. As far as regards 

 the specific names, there is comparatively little difficulty 

 in the application of this simple rule ; but generic names 

 have been used by different authors in senses so widely 

 different, and the groups which they were meant to de- 

 signate have been so variously extended and restricted, 

 that it was no easy matter to determine, where several 

 names had been used, which of them ought to be pre- 

 ferred. 



If the generic name adopted be different from that first 

 employed for the species after the establishment of the 

 Linnean system of nomenclature, the name under which 

 it was first described follows as a synonyme, and where the 

 animal has received more than one specific name, those 

 names are also given, as being sufficient for all purposes 

 of identification ; and to facilitate this kind of reference, 

 the specific names used, are all referred to in the In- 

 dex, followed by an indication of the genus to which 

 they belong. 



These are followed by a reference to a few of the best 

 original figures of the species. 



In those cases where the two sexes of the same spe- 

 cies, or any particular individual state or variety belong- 

 ing to it have been differently named, the name or figure 

 exclusively appertaining to the state or individual is 

 placed after the indication of the specimen to which it 

 applies. 



Great care has been taken by Mr. George Robert Gray, 



