426 TRANSACTIONS OF THE WAGNER FREE 



Pliocene of the Caloosahatchie, Shell Creek and Alligator Creek, Florida, 

 Dall and WiUcox. 



This is alfine species with, in its best condition, very strong radiating ribs 

 with intercalary weaker ones, imbricated irregularly by the lines of growth. 

 The foramen is elongate, keyhole-shaped or oval, and its inner callous border 

 subtriangular, indented medially, behind. It is before the apex of the shell 

 and looks distinctly forward. The shell reaches a length of 55, a breadth of 

 40, and a height of 23 mm. It seems to be especially abundant and fine in 

 the marl at Shell Creek. 



Fissuridea nucula n. s. 

 Plate 19, figures 9, 12. 



Newer Miocene of Duplin Co., North Carolina, near the Natural Well, 

 Burns ; Pliocene of the Caloosahatchie, Dall. 



Shell small, ovate-conic, the sides and ends declining evenly with hardly 

 any arch, the foramen circular, small, its plane nearly horizontal ; sculpture of 

 numerous small, even, elevated, radiating riblets, with about equal interspaces, 

 in which, by intercalation, the ribs gradually appear; these are crossed by 

 little-elevated, rounded threads which minutely crenulate the ribs and sink into 

 the interspaces; the threads are more close-set than the ribs, and the intersec- 

 tions are hardly elevated into nodules ; interior smooth, the muscular impres- 

 sion distinct, the margin minutely crenulate, the foramen rounded, surrounded 

 by a deltoid callus, behind which is an evident dint. Alt. 3.0; Ion. 4.75; diam. 

 3.25 mm. 



This neat little shell seems to be very common in the uppermost Miocene 

 of North Carolina, but rarer in the Pliocene. The specimen figured is from 

 the Pliocene, and happens to be less sharply sculptured than most of those 

 obtained later, in which the interspaces are more distinctly channelled and 

 the beading of the ribs more sharp than the figure indicates. This is shown 

 by the series examined to be merely an individual variation. 



Fissuridea chipolana n. s. 

 Plate 23, figure 21. 



Older Miocene of the Chipola beds near Bailey's Ferry, Chipola River, 

 Florida, and in the lower bed at Alum Bluff, Chattahoochee River, Burns ; 

 Newer Miocene of Duplin Co., North Carolina. 



Shell ovate, slightly wider behind the foramen, with rather straight sides, 

 slightly concave anterior and convex posterior slope ; foramen oval or a little 

 keyhole-shaped, sloping forward ; sculpture of narrow, prominent, radiating 

 rounded ribs, with wider interspaces and alternately smaller intercalary riblets, 

 crossed by distant, regularly spaced, elevated concentric threads, which form 

 nodules at the intersections; these nodules toward the periphery tend to 

 become transversely flattened or pear-shaped, and in large specimens near the 



