ABSTRACT OF PROCEEDINGS. xli. 



-aplite (for aplitic dyke), -micrite (meaning small mass), 

 indicates the definition of the family. A contracted 

 mineral prefix, as bi-(biotite) or hyper- (hypersthene) shows 

 the predominating minor constituent of the genus ; and 

 another prefix the texture which defines the sub-genus. 

 (3) Each name must be distinct and not easy to confuse 

 with others. (4) The names must be as short as possible 

 and easy to pronounce. Since the index minerals of orders 

 cannot be easily stated in a name, root names are given to 

 the orders, but this will involve no tax on the memory, as 

 existing names of the corresponding well recognised groups 

 are used ; e.g.ihe order diorates includes all rocks derived 

 from what is commonly known as the diorite magma. The 

 definitions of accepted groups, granites, gabbros, etc., have 

 not been altered, but only rendered slightly more precise. 

 In conclusion, it is claimed that by use of the privative 

 prefix a- or an-, and by means of other prefixes and suffixes, 

 it is possible to name any igneous rock which may be con- 

 ceived as likely to exist, and also to convey more informa- 

 tion in the name than by any system yet proposed. 



On the motion of Prof. David, seconded by Mr. Siissmilch, 

 it was resolved that the discussion of this paper be 

 postponed. 



On account of the lateness of the hour the reading of the 

 following paper was postponed : — 



3. " On the occurrence of isolated crystals of augite in the 

 tuffaceous mudstones near the top of the Upper Marine 

 Series at Gerringong," by Mr. H. G. Foxall. Com- 

 municated by Prof. T. W. E. David, b.a., f.g.s., f.r.s. 



The President announced that His Honor Judge Docker 

 had kindly offered to deliver a lantern lecture to the mem- 

 bers of the Royal Society on " What I saw in New Zealand;" 

 further particulars as to date etc. would be announced. 



