BY C. JENKINS, L.S. 405 



In the first paper that I had the honor to submit to you I 

 endeavoured to show that the two series of beds respectively 

 named by me the Yass and Hume beds, were unquestionably 

 upper Silurian. 



I propose now to recapitulate the arguments I then used, and 

 add a few other remarks. You have to night the advantage of 

 having before you specimens of some of the rocks and fossils to 

 which I shall refer. 



Whatever progress has been made in learning the Geology of 

 any particular country, it has been done by determining in the 

 first instance the order in which life succeeded life in that part of 

 the world, irrespective of what results may have been arrived at 

 in other near or far distant lands. 



Such was the task I set myself, with regard to the beds about 

 Yass. This task I believe I have in some degree accomplished, 

 examining the strata thoroughly inch by inch from the top to the 

 bottom of the series. 



The conclusion that I have arrived at is that the fossils of these 

 beds correspond more nearly with those of the upper Silurian of 

 England than with those of any other age. 



I arrived at this conclusion from these beds containing in many 

 parts such an abundance of Trilo b ites of exclusively Silurian Genera, 

 without any admixture of Tr Hob ites of exclusively Lower Silurian 

 Genera. 



I concluded also that at least one portion of the series was the 

 equivalent to the lower portion of the Upper Silurian or Llandovery 

 beds of Britain, (taking Sir Roderick Murchison's statement as my 

 guide) from the presence of Trilolites of Upper and Lower Silurian 

 genera, the number of Pentameri, including especially Peutamerus 

 oblong us t the encrinital stems of Lower Silurian type, and the 

 number of Petraia. One Cheirurus is undoubtedly the Cheirurus 

 ins ignis described by Professor Koninck, and determined by him 

 to belong to the horizon of the Llandovery beds. 



