TRANSACTIONS OF WAGNER 

 I 1 60 



TERTIARY FAUNA OF FLORIDA 



PSubgenus Sphenalia S. Wood. 



Shell minute, subquadrate, with the umbones nearly terminal, hinge dis- 

 proportionately small, with two very small and short lamellae in the left valve, 

 a minute resilium between them (probably without a lithodesma), and in the 

 right valve two minute inflected projections of the cardinal margin taking the 

 place of lamellae. Type S. donacina S. Wood. Pliocene and recent. 



Rochefortia Stantoni n. sp. 

 PLATE 43, FIGURE n. 



Miocene of the Natural Well in Duplin County, North Carolina, Burns; 

 Wilmington, North Carolina, T. W. Stanton. 



Shell minute, convex, elongate-ovate, quite inequilateral, the anterior end 

 much longer ; surface with faint incremental lines, polished ; dorsal margin 

 arcuate in front, descending behind the umbo ; ends rounded, an oblique nearly 

 straight bit of margin intervenes between the posterior rounded end and the 

 arcuate base, as if a little of the edge had been shaved off; beaks low, hinge 

 with small lamellar teeth the anterior nearly twice as long as the posterior, 

 resiliary notch small ; adductor scars high, rather large, and distinct ; margin 

 simple, entire. Lon. 3.6, alt. 2.4, diam. 1.5 mm. 



This curious little species recalls R. Verrillii Ball (M. tumidula Verrill and 

 Bush, Proc. U. S. Nat. Mus., xx., p. 781, pi. 94, figs. 1-2, 1898; not of Jef- 

 freys, Brit. Conch., v., p. 177, pi. 100, fig. 5, 1869), but is a much more solid 

 shell, more cylindrical, and less tumid near the beaks. 



These small shells are very puzzling, as their range of variation is for the 

 most part unknown, and they require a good light and strong magnification to 

 bring out their characters. 



Rochefortia Stimpsoni n. sp. 

 PLATE 45, FIGURE 5. 



Miocene of the Natural Well and Magnolia, Duplin County, North Carolina ; 

 Burns. 



Shell small, somewhat compressed, thin, frequently somewhat irregular, 

 and variable in outline; surface marked by obvious incremental lines, not 

 polished, nearly equilateral, rounded, anterior part slightly wider, hinge narrow, 

 resiliary pit directly under the low inconspicuous umbo, with a short recurved 

 oblique lamella on each side of it, the lamellae nearly equal; adductor scars 

 rather large, the anterior smaller; pallial line simple, high up on the disk. 

 Lon. 6, alt. 5, diam. 2 mm. 



