12 March, MorpJwgenesis of certain Pelecypoda. 



show almost pure concentric flank markings with only a 

 hint of posterior development of radial, and the Miocene, 

 like the recent, lose all trace of concentric markings after 

 nepionic stages. 



LITERATURE. 



Bigot. " Contributions a I'etude de la Faune Jurassique de 

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 Soc. Limi. Normand., vol. 17, pp. 261-345. 



, 1894. Ref. to above. Geol. Mag., vol. 31, p. 230, 1894. 



Bl.>\ke, J. F., 1880. "On the Portland Rocks of England." 



Q.J.G S, vol. 36, p. 191, note. 

 Hedley, 1907. "Results of Deep Sea Investigations in the 



Tasman Sea." Rec. Austral. Mtis., vol. 6. no. 4, 1907. 



KncHiN, 1903. "Genus Trigonia." Me»i. Geol. Sui-v. India. 

 Pal. I/idica, ser. ix., vol. 3, no, i. 



■, 1908. "The Invertebrate Fauna and Palaeontological 



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 LvcETT, 1875. "Trigoniie." Pal. Soc. 

 Newton, 1903. "On Bornean Jurassic Shells." Proc. Mai. 



Soc, London^ vol. 5, p. 403. 

 Shattuck, 1903. "The Moll, of the Buda Limestone." U. S. 



Geol. Si (TV. 

 Stremoukhov, 1898. "Russian Mesoz. Trigonise." Bull. Soc. 



Imp. Nat. Moscow. 

 Walford, 1885. "On the Stratigraphical Positions of the 



Trigoniaa of North Oxfordshire." Q.f.G.S., vol. 41,. 



p. 41. 

 Whitfield & Harvey, 1906. " Remarks on and Descriptions 



of the Jurassic Fossils of the Black Hills." Bull. Am. 



Mi/s. N'at. Hist.., vol. 22. 

 Wood, 1899. " Cret. Lamellibranchs." Pal. Soc. 



