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the ventral and posterior surface of the valves of the last-mentioned species ; 
and (3) the shortness and conical nature of the anterior tube and the lesser 
development of the heart-shaped portion from which it originates, in the 
Devonian species. 
Observations . — The majority of Authors have considered the portion 
of Conocardium that is truncate and provided with a tubular prolongation as 
constituting the anterior portion of these shells. Dr. S. P. Woodward was 
the first to express a contrary opinion, an opinion that has found a new 
defender in the person of Mr. D. Etheridge, junior. In spite of the 
respect I have for the works of these savants, and the regard I have for them, 
I cannot agree with their opinion. As I expect soon to have a more favourable 
opportunity than this to elaborate the reasons that compel me to differ from 
them, I will confine myself to remarking that usually the anterior portion of 
the shells of Lamellibranchs is less developed than the opposite portion ; that 
the beaks are directed towards this portion, more rarely gaping and more often 
truncate; that whilst the surface is ornamented with ribs or radiating folds, yet 
the ornaments are broader and thicker on the posterior side of the shell, as is 
readily seen in the Cardiadae, and particularly in Lithocardmm aviculare, 
Lamarck, Cardiuni hemic ardium, Linnaeus, Adacna edentulmn, Pallas, etc., 
and finally, develops and is prolonged more towards the posterior than the 
anterior end. As all these characters obtain in Conocardium, it will be easy 
to draw from them the conclusions to which I have myself arrived. 
Horizon and Localities . — Sowerby and J. Phillips have recorded the 
presence of this species in the Devonian of Stonehouse Hill, and Barton. 
Mr. Clarke has sent me two specimens discovered in the black argillaceous 
limestone of the Yass District, 
Genus— TELLINOMY A, J. Hall. 
Tellinomya Claiikei, L. G. de Koninck. 
PI. Ill, Pig. 8. 
Shell of moderate size, broad, sub-ovate, fairly regularly arched ; beak 
small, little inclined ; posterior end shorter and with a more regularly semi- 
circular outline than the anterior, the contour of which is almost elliptical. 
Surface completely covered by a large number of fine concentric ridges, a 
little thinner towards the summits of the shell tfitm towards the margins. 
