255 



clinal brings it to the surface again, but instances are not frequent. 

 A note on the fossils discovered by me has been supplied by Pro- 

 fessor Tate, appended herewith, and to whom I am also indebted 

 for a determination of the rock specimens. 



Note on the Fossils by Professor Tate. 



1. From the Head of Walker Creek and Mareena Bluff : — 



Orthoceras sp., related to 0. excentricum ] a cast. 



Rayliistoma 1 sp.; casts of three examples. 



Stropliomena sp.; allied to S. funiculata, McCoy, but the 



primary ribs bifurcate. 

 Phacops sp.; a tail-piece about 1^x1^ inches, composed of 



at least six segments. 



2. From Petermaxn Creek : — 



Orthoceras sp., allied to 0. imhricatum, the siphuncle very 



excentric. 

 Orthis Jiabellum. 



There is no community of species between the two localities, 

 though at both the facies is decidedly Silurian. The generic de- 

 terminations of the MoUusca, though probably correct, are based 

 on external resemblances, and therefore subject to revision ; the 

 reference of the Trilobite-tail to Phacops is perhaps less reliable. 

 This uncertainty of the exact generic location makes any specific 

 determination somewhat untrustworthy ; and until a larger num- 

 ber of species have been collected it will be desirable to refrain 

 from an attempt to correlate the formation with any greater de- 

 gree of definiteness, though the balance of the meagre evidence is 

 in favour of Upper Silurian. 



