35 



-tale, and prove clearly enough that several well-defined zones 

 exist among the Australian tertiaries. The diversity of opinion 

 as to the precise position of certain beds in the series is due, no 

 -doubt, in a great measure, to the partial manner in which they 

 have been as yet explored. In the case of the Muddy Creek 

 beds — the most important, perhaps, of the whole series — much 

 confusion has arisen in the past from the mixing together of 

 fossils obtained from two different members of the group. 



It has long been known to collectors of Muddy Creek fossils, 

 that certain species of shells occur only in special portions of the 

 beds ; but as some forms are common to all localities, the varia- 

 tion was thought to be less than it really is. Some observations 

 lately made show, however, not only that the difference is a 

 marked and constant one, but disclose also the important fact 

 that the shells are different according as they are gathered above 

 or below a particular elevation, sections of equivalent height 

 yielding always the same species. When the fossils from the 

 Grange Burn, at Forsyth's (see map), were placed side by side 

 with those from Muddy Creek, at Clifton Bank, and the few 

 species common to both outcrops removed, it became evident that 

 two distinct deposits were represented. 



Examples of the following species are numerous in the first- 

 named place : — 



Triton Quoyi Leda acinaciformis 



Nassa crassigranosa Limopsis Belcheri 



sublirella Pectunculus cainozoicus 



Marginella muscaroides McCoyii 



(aff.) ovulum convexus 



Ancillaria papillata Trigonia Howitti 



Cancellaria Wannonensis Crassatella oblonga 



Terebra catenifera Chione subroborata 



Natica gibbosa propinqua 



Pelicaria coronata Cytherea paucirugata 



Lampania rubricata Dosinia Johnstoni 



Nerita melanotragus Meroe gibberula 



Leiopyrga cingulata Psammobia Hamiltonensis 



Ostrea manubriata Mactra axiniformis 



Mytilus Hamiltonensis Hamiltonensis 



Nucula tumida Corbula ephamilla (var.) 



At Clifton bank there is a much greater variety of species, but, 

 on the whole, fewer individual specimens. The more connnonly 

 occurring forms are : — 



Murex lophoessus Pusionella hemiothone 



Ranella Pratti Pleurotoma perarata 



'Triton Woodsii Haastii 



