440 T. S. Hall — GraptoUte Roclcs, Victoria, Australia. 



many of those of Britain before Professor Lapwortli undertook bis 

 work of revision, they are in very many cases unreliable. The 

 causes that led to this in the British records have been clearly 

 enunciated by Professor Lapworth, and though it must alw^ays 

 appear ungracious to reject any of the work of the pioneers of 

 Australian palaeontology, to whom we owe so much, yet the ground 

 must be cleared before a stable structure can be raised. The 

 minute differences on which it has been found advisable to separate 

 the species in this difficult group were not then generally recognized, 

 and we find many of our graptolites identified with forms from 

 which we now regard them as even, it may be, generically distinct. 

 In the case of those forms where the method of branching and the 

 habit is a guide there was, of course, less liability to confusion, and 

 here the specific identifications are of value, but it is extremely 

 doubtful, on the other . hand, whether any of the Diplograptidae 

 have been correctly determined, and a great number of those forms 

 referred to Didymograptus [sensii stricto) are probably incorrectly 

 identified. One featui'e, however, must not be overlooked, and this 

 is that the records have in many cases been made from exact 

 localities; and this in the case of Sir F. McCoy's papers, owing 

 to his official connection with the Survey, is of peculiar value, as 

 the precise position from which the fossils came is recorded both 

 by him and on the geological maps, and we are thus frequently 

 enabled to check the records in a very eff'ective way. 



During the past seven years I have published several papers on 

 the group as represented in Victoria, and two have also appeared 

 by Mr. G. B. Pritchard, most of them having been printed in the 

 Proceedings of the Royal Society of Victoria. 



In a paper dealing with the occurrence of Lower Silurian (i.e. 

 Ordovician) graptolites in New South Wales, Mr. W. S. Dun ^ gives 

 a list of the more important Australian literature referring to 

 the group. 



Skquence. 



The general sequence of the Victorian graptolites may be correlated 

 with that of the Northern Hemisphere, but experience has shown that 

 it is unsafe to push the analogy too far, and that the only safe method 

 is that of detailed stratigra[)hical work. Thus we find forms here 

 associated which elsewhere are separated by intervening zones ; and, 

 on the other hand, forms elsewhere associated may be here separated. 

 A form which I have named Lepfograptns nntiquns,^ and which, 

 though not pei'baps a typical member of the genus, is certainly 

 not a Didi/mograptiis, occurs on the same slabs as a Bryograptns. 

 Didtjmograptiis bifidns, again, which in Europe and America is 

 characteristic of Upper Arenig, dies out in Australia long before 

 Phyllograptus typvs has disap[)eared, and is also survived by a Clono- 

 graptus and two or three species of Dichograptus. At Lancefield, 

 where our lowest Ordovician rocks occur, Clonograptus flexilis and 



1 Records of the Geological Survey of New South Wales, vol. v (1897). 

 * Proc. Jioy. Soc. \ictoria, new ser., vol. xi (1899), p. 164. 



