KEWTON : OPALIZED SHELLS OF NEW SODTH WALES. 223 



Finally, Mr, F. Chapman,^ Palaeontologist of the National Museum at 

 Melbourne, has quite recently described an opalized tooth of Ceratodus 

 from the Upper Cretaceous opal deposits of Baradine, some 90 miles 

 S.S.E, of Walgett,New South Wales, and has determined it under a new 

 sub-genus and species as Ceratodus {Metaceratodus) u-oltastoni. It is 

 of interest to state that Ceratodus, although chiefly characteristic of 

 Trias and Jurassic times, has been recognized by E. W. Cope in the 

 Fort Union Beds of Montana, United States (Proc. Acad. Nat. Sci. 

 Philadelphia, 1876, pp. 259-60), which are regarded as uppermost 

 Cretaceous or oldest Eocene, as well as in the later Cretaceous deposits 

 of Patagonia, by Ameghino, Dr. A. S. Woodward has further 

 recorded the occurrence of Ceratodus and a Dinosaurian in the Lower 

 Jurassic rocks of Gippsland, Victoria, Australia (Ann. Mag. Nat. 

 Hist., ser. vir, vol. xviii, pi. i, pp. 1-3, 1906). 



An Account of the Opalized Mollusca contained in the Collections 

 OF THE British Museum and the IIev. F. St. J. Thackeray. 



PELECYPODA. 



Fam. CYPEINID^. 



FiSSILUNULA CLAKKEI, Moore, Sp. 



Cytherea clarkei, Moore, Quart. Journ. Geol. Soc., vol. xxvi, p. 250, 



pi. xiii.fig. 1, 1870. 

 Cyprina expansa, Etheridge, Quart. Journ. Geol. Soc, vol xxviii, 



p. 338, pi. xix, fig. 1, 1872. 

 Cytherea clarJcei (= Ci/prina expansa), Tate, 1st Rep. Australasian 



Assoc, 1888-9, p." 230. 

 Cyprina clarkai, Etheridge, jun. : Jack & Etheridge, jun., Geology 



and Palaeontology of Queensland, 1892, pp. 474, 568, pi. xxvii, 



fig. 9; ?pl. xxvi, figs. 18, 19; ? pi. xxvii, figs. 10, 11. 

 Fissilunula clarkei, Etheridge, jun., Mem. Geol. Surv. N.S.W., 



Palaeontology, No. xi, pp. 36-7, pi. vi, fig. 3 ; pi. ix, fig. 1 ; 



pi. X, figs, r, 2 ; pi. xi, figs. 1,2'; 1902. 



Description [original). — Shell large, thick, rather compressed, 

 transversely ovate, inequilateral, modei-ately convex ; umbones 

 flattened, incurved over a large and rounded lunule ; anterior and 

 posterior ends and dorsal margin rounded ; surface of the shell with 

 broad irregular transverse bands of growth. 



Reinarhs. — The specimen referred to this species has parts of both 

 valves preserved in the closed condition, so that no internal characters 

 are exposed, besides which the umbones are, unfortunately, absent. 



' " On a new species of Ceratodus from the Cretaceous of New South Wales ": 

 Proc. Boy. Soc. Victoria, N.S., vol. xxvii, pp. 2-5-7, pi. v, 1914. The genus 

 Ceratodus was reported by Krefit as occurring with Diprotodon remains 

 in the Alluvial deposits of Queensland {Nature, vol. ix, p. 293, 1874), being 

 regarded as an extinct form under the name of C. palmeri, a determination 

 subsequently set aside by C. W. De Vis, who recognized its identity with 

 the recent Ceratodus forsteri of Queensland rivers (Proc. Eoy. Soc. 

 Queensland, vol. i, p. 40, 1884). 



