54 



In the upper beds the existing species amount to nine, eight of 

 Avhich are found in the Australian seas, viz. : — 

 Triton Quoyi, Reeve Chamostrea albida. Lam. 



Placunanomia lone. Gray Neiita nielanotragus. Smith 



Limopsis aurita, BroccJii Fissurella nigrita, Sow. 



Belcheri, Ad. <b E. Amalthea conica, ScJmm. 

 Trigonia acuticostata, McCoy 



The percentage of recent shells in these beds is therefore only 6*5.. 

 which would assign them to the oligocene period. I doubt, how- 

 ever, if the percentage system of classification can be safely ap- 

 plied to either set of beds, while so many forms remain undes- 

 cribed. In the lower zone nummulites occur, and its eocene 

 character may possibly be confirmed by further exploration. 



The geological age of the uj^per beds cannot well be estimated 

 at present, since many species of mollusca obtained from them 

 have yet to be critically examined. The general character of the 

 shells is certainly against their belonging to so early an epoch as 

 the oligocene, and I think it improbable that they are older than 

 miocene. In the case of several, which have received distinctive 

 names, their affinity to existing species is so great that hesitation 

 is felt by palaeontologists in separating them. In the following- 

 table, a list is given of the fossil and living species which are 

 most closely allied. For fuller information the reader is referred 

 to Professor Tate's description of the shells.* 



Species Fossil in Upper Beds 

 IMurex trinodosus 

 Ricinula subreticulata 

 Purpura abjecta 

 Triton ovoideus 

 Peristernia approximans 

 Marginella sp. 

 Nassa sub lirella 

 Pecten subconvexus 

 Mytilus Hamiltonensis 



deperditus 

 Cardita solida 

 Leda acinaciformis 

 Mytilicardia compta 

 Chione subroborata 

 Meroe gibberula 

 Venerupis paupertina 

 Tellina albinelloides 

 Cytherea paucirugata 



Living Analogues. 

 ]\I. Angasi, Crosse 

 Purpura reticulata, Q. (t G. 

 P. textilosa. Lam. 

 T. Bassii, Any as 

 Trophon Paiv^e, Crosse 

 M, ovulum, So^v. 

 N. lirella, Beck 

 P. convexus, Q. and G. 

 M. hirsutus. Lam. 

 M. chorus, Molina 

 C. bimaculata, Deshayes 

 L. crassa. Hinds 

 M. crassicostata. Lam. 

 C. roborata, Hanley 

 M. Alicise, Angas 

 V. exotica. Lam. 

 T. albinella. Lam. 

 C. rutila, Hanley 



Transactions Royal Society of South Australia, 1885-6-7. 



