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1339 



TERTIARY FAUNA OF FLORIDA 



Genus Leptaxinus Verrill and Bush, 1898. Type L. mimitiis V. and B., Proc. 

 U. S. Nat. Mus., XX., p. 797, pi. Ixxxix., figs. 3-5, 1898. 



Shell like Axinulus but with distinct lateral teeth. 



PGenus Ludovicia Cossmann, 1887. Type L. squamula Cossmann, Cat. Illustr., 

 ii., p. 49, pi. ii., figs. 21, 22, 1887. Eocene of the Paris basin. 



Valves rounded-triangular, subcompressed, edentulous, with minute promi- 

 nent umbones. 



The type of the genus Thyasira has a somewhat complicated synonymy : 



Thyasira flexuosa Montagu. 

 Vemis sinuosa Donovan, Nat. Hist. Brit. Sh., pi. xlii., fig. 2, 1801 ; not of Pennant, Brit. 



Zool., iv., p. 95, pi. xciv., fig. SI, 1777. 

 Tellina Hexuosa Montagu, Test. Brit., p. 72, 1803. 

 Amphidesma Aexuosa Lamarck, An. s. Vert., v., p. 492, 1818. 

 Thyasira Hexuosa Lamarck, as of Leach, loc. cit., in synonymy. 

 Lucina sinuata Lamarck, op. cit., v., p. 543, 1818; Hanley, Cat. Rec. Sh., p. yy, 1844. 

 Ptychina biplicata Philippi, En. Moll. Sicil., i., p. 15, 1836; ii., p. 4, 1844. 

 Lucina sinuosa Thorpe, Brit. Mar. Conch., p. 74, 1844; not of Roemer, Paleontographica, 



iii., p. 32. 

 Cryptodon bisinuatus S. Wood, Ann. Mag. N. Hist., vi., p. 247, Nov., 1840; Crag Moll., 



ii., p. 134, pi. xii., f. 20 a-b, 1853. 

 Axinus sinuatus Philippi, Zeitschr. Malak., 1845, p. 91. 



TAxinus Sarsii Philippi, loc. cit., 1845 ; Loven, Ind. Moll. Scand., p. 38, 1846. 

 f'^Axinus flexuosus van rotunda Jeffrys, P. Z. S., 1881, p. 701. 



Fossil in European Neocene and Pleistocene, also recent in northern Eu- 

 rope, the North Atlantic south to the Canaries and Azores, the Mediterranean ; 

 PGreenland, not Labrador and northeastern North America ; two to five hun- 

 dred fathoms. 



Donovan's figure appears to me to be taken from a distorted specimen of this 

 species, of which there are several in the Jefifreys collection, but his name was 

 preoccupied for another species by Pennant, which Montagu recognized in 

 renaming it flexuosa. Jefifreys unites several forms which appear to me dis- 

 tinct under the head of this species, and has been followed by Posselt (Consp. 

 Fauna Gronl., p. 80, 1898). Among these are the T. Sarsii Philippi, which is 

 known from north Europe and Greenland but not from America, east or west. 

 The shell regarded as a variety rotunda by Jeffreys is a deep-sea form near to 

 T. equalis Verrill and Bush, but less truncate behind, the T. Gouldii Philippi 



