TRANSACTIONS OF WAGNER 

 1 144 



TERTIARY FAUNA OF FLORIDA 



margin depressed in front of the beaks, nearly straight for a short distance, 

 then rounding evenly to the anterior end; base arcuate, posterior end more 

 bluntly rounded, with the posterior dorsal margin arcuate and high; hinge- 

 plate narrow, channelled, with a short obscure anterior lamella, whose " hook" 

 is represented by a small pustular elevation; posterior lamella long, arcuate, 

 almost fused with the margin but rising distally to a small elevation ; interior 

 of the valve smooth or with faint radial lines ; adductor scars narrow, long, 

 extending well down towards the base. Lon. 9.5, alt. 7, diam. 2.2 mm. 



Two left valves of this well-marked species were found in the marl. The 

 other species described from this horizon are much smaller and more inflated, 

 and the young of E. plicatula, judging by the incremental lines, had a different 

 outline from either of the others. 



Erycina undosa n. sp. 



Plate 45, Figure 3. 



Oligocene of the Chipola beds at Alum Bluff and on the Chipola River, 

 Calhoun County, Florida ; Burns and Dall. 



Shell small, compressed, polished, Senielc-iorm, anterior end rounded, 

 longer ; posterior end shorter and more bluntly rounded ; beaks low but rather 

 pointed ; surface with equidistant concentric impressed lines separating wider, 

 flattish interspaces ; hinge strong, teeth normal ; adductor scars large, the 

 pallial impression wide and slightly irregular. Lon. 3.5, alt. 2.8, diam. 1.5 mm. 



The shell varies somewhat in proportional length and some specimens may 

 reach 4.5 mm. 



Erycina chipolana n. sp. 



Plate 44, Figure 15; Plate 45, Figure 17. 



Oligocene of the Chipola marls of Alum Bluff and the Chipola River. 

 Calhoun County, Florida ; Burns and Dall. 



Shell small, compressed, smooth, polished, donaciform; posterior end 

 shorter and with more abrupt descent of the dorsal margin ; beaks rather low, 

 hinge strong, the distal portions of the laminae prominent with a marked 

 groove above them ; posterior adductor scar larger and lower down than the 

 anterior; basal margin arcuate. Lon. 4.1, alt. 3.0, diam. 2 mm. 



The principal characteristic of this small species is its trigonal shape; the 

 laminae are also more prominent than usual. 



