NKWTON : OPALIZED SHELLS OF NEW SOUTH WALKS. 221 



converted into precious opal (6 inches in diameter), unfortunately 

 since destroyed in a conflagration, but which was once in the 

 Geological Survey Museum of New South Wales. The preservation 

 of some of these fossils is excellent, although all are not alike in this 

 respect, and the extent to which the opalization has at times been 

 carried is remarkable". Considerable colour efiPects are visible by 

 reflected light, Mr. Etheridge having noticed "principally blue, red, 

 green, and yellow, with their various shades and combinations, not 

 the least pleasing being an ever- varying degree of red and blue-tinted 

 purple ". 



In the succeeding year two opalized Pelecypods from White ClifFs 

 were described by the late Professor Ralph Tate ^ as Lucina (?) 

 honythoni and Platopis (?) corrugata, both being regarded as new 

 species and of Upper Cretaceous age. The late Professor H. G. Seeley ^ 

 referred in the same year to the humerus of a Plesiosaurian from the 

 opal-mines of White Cliffs, in which " the substance of the bone was 

 almost entirely replaced by opal" ; this specimen, it is interesting to 

 state, is now in the Mineral Department (No. 83630) of the British 

 Museum. Mr. G. Giirich,^ of Breslau, next published an account 

 of some Mollusca, a vertebra of Plesiosaunis, and fossil wood 

 {Araiicarioxylon sp.) fi-om the same opal deposits, and regarded them 

 as of younger Jurassic age, the molluscan species being as follows : — 



Avicula barkli/i, Moore. 



Trigonia sp. cf. moorei, Lycett. 



Cgrena{?), n.sp. 



Teredina opalina., Giirich. 



Gresslya sp. cf. gregaria, Goldfuss. 



Natica variahilis, Moore. 



Belcmnites /cleitii, Giirich. 

 The more complete account, however, of the palaeontology of the 

 White Cliff's opalized beds was that contributed by Mr. Etheridge, 

 jun.,* in 1902, which included a bibliography, as well as descriptions 

 and figures of new and little-known species of Mollusca embracing 

 the establishment of two new genera of Pelecypoda, viz. Fisstlmiula 

 and Cyrenopsis. The list of species included the following forms : — 



Ckinoidea. 

 Isocnnus australis, Moore, sp. 



Pelecypoda. 

 Maccoyella harklyi, Moore, sp. 

 Inoceramus sp. 

 Modiola dunlopensis 

 Modiola tatei '- Etheridge, jun, 



Modiola sp. indet. 

 Ct/reiiopxis opallifex 



^ Trans. R. Soc. S. Australia, vol. xxii, pt. ii, pp. 77-9, text-figures, 1898. 

 ^ Quart. Journ. Geol. Soc, vol. liv, Proc, p. cvi, 1898. 

 •■' Neues Jahrb., Beilage Band xiv, pi. xix, pp. 484-500, 1901. 

 ^ Monograph of the Cretaceous Invertebrate Fauna of New South Wales (Mem. 

 Geol. Surv. N.S.W., Palseontology, No. xi, 1902). 



VOL. XI.— iLVRCH, 191-5. 1(5 



