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TERTIARY .FAUNA OF FLORIDA 



Thyasira trisinuata Orbigny. 



Lucina trisinuata Orbigny, in Sagra, Moll. Cubana, it, p. 300, pi. xxvii., figs. 46-49, 1846. 



fLucina flexuosa Fischer, in Beau, Cat. des Coq. rec. a la Guadeloupe, p. 23, 1857. 



Axinus flexuosus 'var. polygona Jeffreys, Brit. Conch., ii., p. 248, 1863. 



Cryptodon obesus Verrill, Am. Journ. Sci., iii., p. 287, pi. vii., fig. 2, 1872 (non G. O. 

 Sars, 1878) ; Trans. Conn. Acad., iii., p. n, pi. i., fig. n, 1874; Rep. Inv. An. Vine- 

 yard Sd., pp. 509, 687, pi. xxix., fig. 214, 1874 ; Proc. U. S. Nat. Mus., iii., p. 399, 1880 ; 

 Trans. Conn. Acad., v., p. 569, 1882; Dall, Bull. U. S. Nat. Mus. No. 37, p. 50, pi. 

 Iviii., fig. 12, 1889. 



Thyasira trisinuata Dall, Synopsis of Lucinacea, p. 786, 1901. 



Rare in the Pliocene marls of the Caloosahatchie and Shell Creek, Florida, 

 Dall, Willcox, and Burns ; living from Labrador to Martinique in the western 

 Atlantic in fifteen to two hundred fathoms, and on the northwest coast of 

 America at Sitka, Alaska, in ten fathoms, and on the coast of Korea, St. John. 



This widely distributed form is rare in the Pliocene marls and attains a 

 larger size as we follow it northward or into the colder water of the deeps. 



A minute shell about one millimetre in diameter, ovate, smooth, edentulous, 

 and moderately convex, was found in the Claiborne sand. If certain that it 

 is adult, I should be disposed to refer it to the section Axinulus, but I have a 

 suspicion that it is merely the nepionic young of a species of Lucina, and so 

 prefer to await further information before giving it a name. 



FAMILY LUCINID^. 



The first elimination of forms belonging to this family from the heterogene- 

 ous groups of the pioneer authors was by Scopoli (1777), who Latinized Adan- 

 son's native name in the form of Codakia, with Adanson's species as the type. 

 The species is somewhat doubtful, since Deshayes '(An. s. Vert., ed. ii., vi., 

 p. 318) identifies it with Lamarck's Cytherea interrupta (which Reeve denies), 

 and other authors with Venus orbicularis or V. tigerina of Linnaeus (1758). 

 It appears to be certain, however, that it is generically identical with both of 

 the last two mentioned, and if specifically the same as either of them, probably 

 with the former of the two. 



Bruguiere in 1792 had not discriminated either of the Lucinoid genera, but 

 in the volume of plates to the Encyclopedic Methodique which appeared in 

 1797 there are two plates of species belonging to this group with the legend 

 '"Lucina." The genus was adopted by Lamarck in 1799, who describes it and 

 cites a single example, the Venus edentula of Linnaeus. This must therefore 

 be considered as the type, as already recognized by Fischer in his " Manual." 



