64 Proceedivjjs of tJic Royal Hocieti/ of Victoria. 



sometimes very sandy, but generally it is wholly composed of a 

 mixed mass of comminuted fragments of polyzoa." 



At the Dog Rocks section the limestone is inaccessible, except 

 at its highest portion, and slopes away from the nearly vertical 

 Silurian strata. We examined its contents by means of the 

 blocks which have fallen down from above on to the silurian 

 floor of the river-bed. It is, as Mr. Wilkinson says, crowded 

 with polyzoa, but the determinable moUuscan remains are very 

 few, and the rock is so hard that we could only break out 

 fragments of the fossils showing on the surface of the blocks. 

 Amongst them we determined : — 



Spondylus pseudoradula Pecteu polymorphoides 



Ostrea sp. Pecten sp. 



Pseudamussium hochstetteri ? Terebratula sp. 



Pecten subbifrons Cidaris sp. (spines) 



In the quotation from Mr. Wilkinson just given, he alludes to 

 these limestones as " Upper," and distinguishes them from the 

 clays with gastropods, etc., which he terms "Middle" Miocene 

 (Eocene). Certainly the polyzoal limestone of the Dog Rocks is 

 at a higher level than the clays, etc., of the amphitheatre. 

 According to our measurements, a horizontal line carried from 

 the base of the polyzoal strata in the former section would just 

 cut the top of the horizontal banded limestone in the latter. 

 Apparently the polyzoal strata are also horizontally disposed, 

 but the section is a short one, and a slight dip in some direction 

 may possibly exist. Probably, therefore, in terming such beds 

 the " Upper," and those of the amphitheatre the " Middle," 

 Mr. Wilkinson only intended to convey the idea of superposition 

 for the polyzoal rocks, and not to assert that any marked 

 difterence of geological age existed between the two sets of 

 strata. In reference to this question of superposition for the 

 strata under consideration, we simply remark that no actual 

 contact of the polyzoal rock with the marls and limestones of the 

 amphitheatre type was observed by us at any section on the 

 river ; and, in the absence of such contact, we cannot venture 

 to pronounce on the actual sequence of the beds. Pala^onto- 

 logically, we hold them to be inseparable, basing our opinion, as 

 far as the polyzoal rock is concerned, not merely on the few 



