TRANSACTIONS OF WAGNER 

 898 



TERTIARY FAUNA OF FLORIDA 



Spisula (Hemimactra) duplinensis n. s. 

 PLATE 30, FIGURE i. 



Chesapeake Miocene of Duplin County, North Carolina ; Willcox. 



Shell subovate, thin, moderately inflated, beaks subcentral, not prominent, 

 adjacent; surface smooth, except for incremental lines, which are most promi- 

 nent towards the ends ; the middle of the valve is more or less polished, 

 anterior end somewhat shorter than the posterior, both moderately rounded ; 

 dorsal slope nearly equal on both sides of the beak ; dorsal areas obscure, 

 the posterior smoother and more impressed; hinge much as in S. marylandica, 

 but the pit larger and with a more projecting ventral margin ; pallial sinus 

 reaching forward more than half the length of the shell, pointed in front ; 

 basal margin curved but not arcuate. Lon. 58, alt. 42, diam. 22 mm. 



This species at first sight looks very close to 5. marylandica, but has a 

 longer pallial sinus, less prominent beaks, more equal dorsal slopes, and less 

 arcuate basal margin. The lateral laminae are finely granulated, and not 

 striated, which separates it at once from the siniilis group, and the propor- 

 tions are quite different from those of the young -S. polynyma Stm. of the 

 same size. It is probably the shell referred to S. similis Say by Tuomey and 

 Holmes (Pleioc. Fos., p. 97, pi. 23, fig. 8) and Emmons. 



Spisula (Hemimactra) curtidens n. s. 

 PLATE 27, FIGURES 2, 24. 



Chesapeake Miocene of Burch, on the Patuxent, and near Easton, on the 

 Choptank River, Maryland; of Magnolia, Duplin County, North Carolina; 

 Burns. 



Shell large, not heavy, subtrigonal, with low, narrow, rather pointed 

 beaks, the anterior being markedly longer than the posterior end; surface 

 smooth or striated by incremental lines, and near the base by fine, obscure, 

 irregular longitudinal wrinkles ; valves moderated, inflated ; anterior end pro- 

 duced, depressed above, rounded in front; posterior end short, flattened in 

 front of the beaks, posterior dorsal area impressed and bounded by a rounded 

 ridge which extends from the beak to the margin ; anterior dorsal area im- 

 pressed, with a somewhat flexuous surface; hinge with a large but not pro- 

 jecting chondrophore ; in the right valve the dorsal lamina; are very short 

 and smooth, the cardinal tooth quite compressed. Lon. (of young shell) 22, 

 .ill. 17, diam. about 9 mm.; but judging from the fragments found, the species 

 reaches when adult a height and length of 90 mm. 



