March, 1^07.] f HE VICTORIAN NATURALIST?, 23? 



ON THE OCCURRENCE OF YERINGIAN FOSSIL- 

 IFEROUS MUDSTONE AT CROYDON. 



By F. Chapman, A.L.S., &c., Palaeontologist, National Museum, 



Melbourne. 



{Read be/ore the Field Naturalists'' Glub of Victoria, ilth Feb., 1907.) 



The younger series of Silurian rocks in the vicinity of Melbourne 

 was formerly partly referred to the Bala beds, and partly to the 

 Wenlock series, by Sir F. McCoy.* At the time when McCoy 

 expressed this opinion very little was known of the actual fauna 

 of these beds. Since then, owing to the work of Mr. R. 

 Etheridge, jun., and others. Prof J. W. Gregory found it possible 

 to distinguish a higher series than the group of sandstones and 

 shales of the Melbourne area (Melbournian), which he called the 

 Yeringian.f So far as our present knowledge of its fauna allows 

 us to speak, the Yeringian beds probably represent both the 

 Wenlockian (in part) and the Ludlovian of Great Britain and 

 adjacent areas. It may, as in that country, be capable of further 

 subdivision, the lower or typical Yeringian beds being developed 

 round Lilydale, the upper in the shales of the Upper Yarra and 

 near Tanjil. The Yeringian series are characteristically seen in 

 the neighbourhood of the Yarra Flats, where they appear to lie 

 in a synclinal fold on the Melbournian (older Silurian) series. 

 At Lilydale there is a lenticular mass of limestone, yielding many 

 corals and gastropods, and both towards Mooroolbark and 

 Seville this seems to pass very rapidly in a horizontal direction 

 into a hard mudstone rock. In the Yering district the rocks are 

 chiefly yellowish or ochreous mudstones, containing an interest- 

 ing brachiopod fauna : the fossil shells in many cases still remain 

 very little altered. Near Seville the beds are represented by a 

 hard mudstone, in which the fossils are only found as moulds and 

 casts, often, however, very faithfully preserved, whilst in the same 

 district, farther to the east, an impure limestone of a dark blue 

 colour is found, which yields many corals and trilobites. 



Up to the present time no record has been made as to the 

 occurrence of Yeringian beds so far south of Lilydale as Croydon, 

 and therefore the following notes have been written, showing that 

 Yeringian mudstones containing fossils similiar to those of the 

 Yering district are found between Croydon and Mt. Dandenong, 

 about 8 miles to the south-west of the nearest previously known 

 locality — namely, that ne^ir Seville. | 



* Intercol. Exh. Essays, Recent Zool. and Palreont. of Vict., 1867, 

 p. 23 (p. 329). 



t Proc. R. Soc. Vict., vol. xv., N. S., part ii., 1903, p. 172. 



t Proc. R. Soc. Vict., vol. vi., N.S., 1894, p. 156. The Rev. A. W. 

 Cresswell, M.A., who, excepting the earliest geological sui-veyors of Victoria, 

 probably collected and recorded more material from the Yering district than 



