NEWTON : OPALIZED SHELLS OF NEW SOUTH WALKS. 229 



Locality.— ^\nte Cliffs, New South Wales. 



Collectio7is. — British Museum (Mineral Dept. iW? ; Geol. Dept., 

 G. 19603). 



CyKENOPSIS (?) ELONGATA, 11. Sp. PI. VI, FigS. 17, 18. 



Description. — Shell thick, robust, subtrigonal, oval, length nearly 

 \^ times the height, valves compresso-convex ; umbones anterior, 

 incurved ; posterior region elongate, sloping, probably subaiigulate, 

 anterior extremities rounded, short, ventral margins elongately 

 curved ; sculpture consisting of rather coarse, concentric, elevated, 

 rounded growth-periods with tine concentric interlineations, crossing 

 which are a series of short, equidistant, raised, filiform, vertical 

 striations. 



Dimensions (closed valves). — Length 32, height 24, diameter 15 mm. 



Remarks. — The shell of this specimen has been partially removed by 

 fracture from the dorsal region, especially beneath the umbones, and 

 posteriorly where the areal surface within the margins is quite lost. 

 Otherwise it consists of a i)air of valves in the closed condition, the left 

 lateral surface showing a well-arched umbonal region, and the surface 

 exhibiting interesting details of sculpture. The growth-bands are 

 more or less raised and feebly convex, while the general surface is 

 covered with fine concentric striations, except where erosion can be 

 traced, when such maikings have become obliterated. The short 

 vertical striations, observable in the ventral region more particularly, 

 areof filiform character, and like a similar structure noticed previously 

 in Cyrenopsis yneeki, Etheridge, jun. 



I have no doubt at all as to the fresliwater origin of this shell, and 

 chiefly from the peculiar character of the ornament, which indicates 

 a slight uncertainty or irregularity in the design of the concentric 

 lineations, a similar plienomeuon existing in most Pelecypod shells of 

 the same habit, and in this way differing from marine forms, which 

 generally show a greater decision in their sculpture markings. As 

 no dental characters are preserved, this shell is associated provisionally 

 with the genus Cyrenopsis; it appears to differ chiefly from other 

 species in possessing a more elongately oval contour. 



Locality. — White Cliffs, iS^ew South Wales. 



Collection. — Rev. F. St. J. Thackeray. 



COEBICDLA CORKUGATA, Tate, Sp. PI. VI, FigS. 15, 16. 



Platopis (?) corrugata, Tate, Trans. Hoy. Soc. S. Australia, vol. xxii, 



p. 79, text-figures, 1898. 

 Cyrenopsis (?) corrugata^ Etheridge, jun., Mem. Geol. Surv. New 



South Wales, Palgeontology, No. xi, p. 30, 1902. 

 Description {original). — Shell transversely triangular, somewhat 

 cuneiform, convexedly depressed. Umbones large, obtuse, ante- 

 median ; lunule ill-defined. The dorsal slopes straight, inclined at 

 an angle of 95°, the posterior considerably the longer; post-ventral 

 extremity roundly pointed, the ventral margin nearly straight to 

 beyond the middle line, thence curving rapidly upwards to form the 

 well-rounded anterior extremity. The post-dorsal line is bounded by 



