proposed, and one that is not open to more objections than 

 made to any other. And also it is, I think, the one most 

 ally used. To apply it consistently, however, compels the rej 

 of binary terms — such as Quartz-felsite — for the groups, and in 

 the selection of names to replace them geologists should be guided 

 by the rules which have conferred so much benefit on nomenclature 

 in Biology. It may be unimportant by what name we call a rock, 

 but it is very important that all geologists should call it by the 

 same name, and that no new name should be proposed as a substi- 

 tute even if the new name be more classically formed. And it is 

 the law of priority, so strongly ai ' ' ' ' 



i 



gists, which alone can give us permanency 



.^.., ^- -~--^- No 



should be considered 

 is of little real importance. Respect for the law of priority 

 only way by which we can escape confusion. Perhaps the 

 name suggests the better it is. Many names in I^iology are 



L for tlie felhitic obsidians only. 

 Liysis is rarely availal)le as a help towards the clas; 

 N<'w Zealand eruptive rocks and T have had 

 Titirely on mineral composition and specific gravit 





