MAR 3 1899 



7T 



On T^wo New Cretaceous Bivalves. 



By Professor Ralph Tate. 



[Read August 2, 1898.1 



Lueina (?) Bonythoni, sp. nov. (1898). 



Shell large, triangularly oval, with depressedly convex (right) 

 valve. Umbo a little in front of the middle, moderately large, 

 incurved in a transverse direction ; lunule almost obsolete. 

 Posterior and anterior dorsal slopes making an angle of 110°; 

 the posterior one straight, the anterior one slightly incurved, and 

 shortly and bluntly extended at its junction with the semi-circular 

 ventral margin, the post-ventral margin rounded. 



The ornamentation consists of acutely - rounded radial 

 threads and concentric thread-like lamellae, forming by their 

 combination a cancellated surface-structure of oblong or nearly 

 square depressions, which extends over the whole surface. The 

 thread-like margins of the concentric lamellae are feebly vaulted 

 on the radial threads. Towards the ventral margin in the medial 



line, there are about eight 

 radial threads, and about nine 

 concentric threadlets in a 

 square of 5 millimetres. 



Dimensions. — Antero-pos- 

 terior diameter 4*5 ; ventro- 

 umbonal diameter 4"0 ; post- 

 dorsal and antero-dorsal slopes 

 about 2*5 mm. 



Habitat. — One right valve, 

 the test of which is replaced 

 by Precious Opal. Upper 

 Cretaceous at White Cliffs, New South Wales ; the unique type 

 in the Museum of the School of Mines at Adelaide. 



The species-name is in compliment to Sir J. Langdon Bonython, 

 Chairman of the Council of the School of Mines since 1890. 



Remarks. — The only shells figured from Australian Cretaceous 

 rocks at all comparable with the present species, apart from any 

 presumptive generic affinity, are Lueina anomala and L. ? aus- 

 tralis, Moore, in Quart. Journ. Geol. Soc, xxvi, 1870 ; more so 



