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779 



TERTIARY FAUNA OF FLORIDA 



fined to a very small space near the umbo, and inconspicuous ; crura of the lower 

 valve small, forming an acute angle, well elevated, the socket for their recep- 

 tion on the opposite valve shallow. Alt. about 50, lat. 50, diam. about 8 mm. 

 This form is distinguishable at once from the Pliocene and recent species 

 by its peculiar surface sculpture. 



Genus PODODESMUS Philippi. 

 Pododesrmts Phil., Wiegm. Arcliiv., i., p. 3S5, 1837 ; Handb. der Conch., p. 380, 1853. 



Type P. decipiens Phil. = P. ritdis Brod. 

 ? Tedinia Gray, P. Z. S., 1851, p. 197 ; Cpr., Maz. Cat., p. 165, 1857. 

 Placunanomia pars, Broderip, Gray, Carpenter, Reeve, et al. 



Pododesmus rudis Brodeiip. 

 Placu7ianomia rudis 'ByoA. , P. Z. S., 1834, p. 2; Reeve, Conch. Icon., pi. i, fig. 2, 1859. 

 Pododesmus decipiens VhW. , Wiegm. Archiv., i., p. 387, pi. 9, fig. i, 1837. 

 Placimanomia echinata Bred., /. c; Reeve, Conch. Icon., pi. i, fig. i, 1859. 

 Placimanomia abnormalis Gray, P. Z. S., 1849, p. 121 ; Reeve, Conch. Icon., pi. 3, fig. 



lifU-b. 

 Placunanomia {Pododesmus') ritdis Gray, P. Z. S., 1849, p. 120. 

 Placunanomia Harfordi'Sj&^v^, Conch. Icon., pi. 2, figs. 8«, 8^, 1859. 

 ? Placunanoinia Gorildii 'R.e.cvc, op. cit., pi. 3, fig. \oa, b, 1859. 



? Chipola Oligocene of the Chipola River, Florida ; Dall. Recent from 

 Cedar Keys, Florida, through the West Indies, and south to the mouth of the 

 La Plata River, South America. 



This shell resembles Anomia acideata externally, from which it is dis- 

 tinguished by its small, often obsolete, byssal foramen, and by having only 

 two muscular impressions, — one large and conspicuous, which is the mark of 

 the modified byssal muscle, and another below it, smaller and hardly distin- 

 guishable on a fresh polished specimen, which is due to the adductor. It is 

 likely that the Chipola species is distinct and could be properly characterized 

 when adult, but the two upper valves obtained are quite young, and offer 

 absolutely no characters by which they can be differentiated from P. rudis of 

 the same size. I have therefore thought it best to refer the form to P. ritdis 

 until more material is available. The relative position of the scars in the 

 Anomiidic changes with age. 



Pododesmus scopelus n. s. 

 ■ Plate 30, Figure 8. 



Uppermost Oligocene of the Alum Bluff beds, at Rock Bluff, Chatta- 

 hoochee River, Florida ; Dall. 



