T. S. Hall — Graptolite Rocks, Victoria, Andralia. 441 



C. rigidus are found in association with Bryograptus, while in 

 Europe and America Bryograptus is a Cambrian form, and indicates 

 an age to which its Victorian associates forbid us to refer it here. 

 In the Northern Hemisphere, again, Glonograptus flexiUs is associated 

 with forms which characterize the next higher horizon with us. 

 The case of G. rigidus is also striking, for though in America it is, 

 according to Ami,^ associated with Loganograptus, yet with us the 

 latter genus does not appear till PhyJlograptus typus and closely 

 allied species have become extinct. These are all striking forms, and 

 although it is of course not impossible that mistakes in identification 

 have been made, yet figures and descriptions of Australian forms 

 referred to these species have been published by McCoy and myst-lf, 

 with the exception of the members of the tuning-fork graptolites. 



The stratigraphical evidence on which these statements are founded 

 does not rest on merely a single set of outcrops, for, with the 

 exception of the Lancefield beds, the field relations of which have 

 not yet been worked out, as the conditions are unfavourable, their 

 relative position has been studied in two or three places. 



To prove a negative is, of course, not an easy task, and it may be 

 objected that the non-association of some of the forms I have quoted 

 is only due to imperfect collecting. For instance, I have placed the 

 Castlemaine rocks as a whole above those of Bendigo, and both 

 above those of Lancefield. and have never seen Clonograptus fle.tib's 

 anywhere but at Lancefield, where G. rigidus occurs as well. 

 A species related to the latter, which, however, I believe to be distinct, 

 ranges up into the lower Castlemaine zones, but never as high as 

 beds which contain Zoganngraptus Logarii. This statement is founded 

 on several years' collecting in fairly rich beds at Castlemaine and 

 Bendigo, as well as on the examination of several collections made 

 at the latter place by others, so that the evidence in favour of the 

 facts being as I believe them to be is strong. 



The numerous localities at which graptolites occur in Victoria and 

 the vast area over which they are spread render the hope of any- 

 thing like a complete account of them for some time to come quite 

 out of the question, and all that can be done at present is to give 

 a brief outline of what has been done towards elucidating their 

 sequence. There is not at present sufficient evidence available to do 

 more with the Ordovician rocks as a whole than to divide them into 

 Upper and Lower, the upper division being characterized by the 

 presence of Dicranograptid83. 



The most thorough collecting that has been done is in the older 

 beds of the Lower Ordovician, and even here large areas are almost 

 untouched. The younger beds of the series have not as yet yielded 

 many forms in a sufficiently well-preserved condition for description, 

 while those from the Upper Ordovician occur at widely scattered 

 localities, and the collections made are email and poox\ Still worse 

 is the case of the Silurian forms, for they come from some half-a-dozen 

 localities and afford little more than a record of Monograptus and 

 Eetiolites. 



^ Geol. Surv. Canada, Ann. Rep., vol. iii (1887-8), K, p. 116. 



