INSTITUTE OF SCIENCE, PHILADELPHIA. 24 E 



the last whorl or two, next the suture, runs parallel with it, except as it is 

 undulated by the ends of the ribs. 



Nassa Johnsoni n. s. 

 Plate 13, figure 12. 



Cape Fear River, North Carolina, Johnson, from the marl-bed at Mrs. 

 Purdy's ; and also from the Natural Well, Duplin Co., Burns. 



Shell short, inflated, with a pointed but little-elevated spire and about 

 seven whorls ; nucleus lost in the types ; early whorls with six or seven nar- 

 row, strap-like, revolving elevated lines, of which two are more prominent; 

 later the prominent lines take on a more carinated appearance, and are rein- 

 forced by numerous smaller ones ; on the last whorl this pre-eminence is 

 obsolete and the spiral sculpture recalls that of TV. consensa, consisting of very 

 numerous continuous, even, narrow threads alternating in the proportion of 

 one slightly more prominent followed by three to five finer and then another 

 slightly larger one, the interspaces being equal to or slightly wider than the 

 threads; transverse sculpture of numerous (on the last whorl i8 to 20) 

 rounded ribs extending from the suture to the siphonal carina, with the inter- 

 spaces equal or wider on the last and narrower on the early whorls ; suture 

 distinct, not channelled, toward the last laid over an edge of body callus ; 

 whorls rounded, aperture longer than the rest of the shell, wide, semi-lunar, 

 narrow and pointed behind, with an obtuse subsutural callus ; body with a 

 broad, thick, smooth callus ; pillar concave, with a prominent anterior keel, 

 shorter than the outer lip ; siphonal notch deep, with the usual nassoid keel ; 

 outer lip little reflected, moderately thickened, simple, with about fifteen short 

 denticular lirse just within ; throat without lir^. Lon. of shell 22 ; of 

 aperture 13.5; max. lat. of shell 15 5 mm. 



This fine species is related to " Ptychosalpinx" scalaspira and " Par-a- 

 iiassa" harpidoides Conrad. 



N. scalaspira was described from a broken specimen, but is destitute of 

 the fine sharp spiral sculpture and has fewer ribs and a higher, more scalar 

 spire than N. Johnsoni. The proportions of TV", harpuloides are quite different, 

 especially about the aperture, while the pillar is quite unlike that of N. 

 Johnsoni. 



The species is named in honor of Mr. Chas. W. Johnson, to whose suc- 

 cessful researches we owe much valuable information as to the Tertiaries of 

 the Carolinas. 



It may be added that Tritia {Bttccinjim) prcerupta Conrad appears to be 

 synonymous with Nassa impressa H. C. Lea, and that the latter, which is a 

 young and imperfect specimen, has much the aspect of a youthful N. bidentata 

 Emmons. 



