Terlianj.l PALEONTOLOGY OF VICTORIA. \^Mollusca. 



sculpturing to vary, and this species is the most extraordinarily 

 varialjle in the sculpturing of the right valve that I know. The 

 left valve presents little variety in this resjiect, but in the variety 

 semi-lcBvis which I have now figured, the right valve is quite smooth, 

 while the left valve, attached still to it, is of the ordinary typical 

 chai'acter ; generally this valve is completely and strongly radiated 

 with sub-equal, round, nearly smooth ridges, as in the original type 

 of the species, while a specimen from Mordialloc has all the rostral 

 portion smooth, and the marginal portion radiatingly ridged, thus 

 uniting the two extreme varieties. 



In size, sliai^e, form of ears, relative convexity of the two valves, 

 and the numerous narrow scaly ridges of the flatter one, this fossil 

 resembles the well-known German Miocene Tertiary species, the 

 Pecten Hofmanni of Goldfuss from Biinde in Westphalia, so nearly, 

 that at first sight one might mistake one for the other ; the ridges, 

 however, are slightly larger, usually more nearly equal, and less 

 rigid in this species, which is totally chstinguished by having the 

 right or deeper valve chft'erent from the other, while they are both 

 alike in the P. Hofmanni. The convexity of the left valve is 

 sometunes greater than m the specimen figured and desci'ibed. 



Small and rare in Lower Pliocene beds of Brighton Beach, near 

 Mordialloc. 



Extremely abundant in the Miocene Tertiary sandy beds on the 

 shores of Corio Bay, A" 15. 



Common, A'' 22. Common with the two valves together of lai'ge 

 size in Miocene sandy beds of Bamisdale, Mitchell River. At 

 (A"' 10) ; in the sandy beds of Middle Miocene Tertiary on coast 

 1 mile W. of Sherbrook River, 37 miles E. of Warruambool ; of 

 large size at A" 28 and A" 12. 



Very rare in Oligocene Tertiary clays near foot of Mount Eliza. 



Explanation of Figures. 



Plate XXXIV. — Fig. 1, right valve, of unradiated variety, natural size. (The figure has 

 been reversed in the lithographing.) Fig. I«, profile view of same specimen, natural size. Fig. 

 14, left valve of same specimen, natural size. (Also reversed in the lithograph.) Fig. \c, 

 portion of surface of unradiated valve of this variety, magnified. Fig. Id, portion of left valve, 

 magnified. 



Frederick McCoy. 



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