INSTITUTE OF SCIENCE, PHILADELPHIA. 47 



This fine shell differs from any of the previously described Tertiary species 

 of our Atlantic region. It does not resemble the A. glabrata,\h& only form 

 now known from the Floridian region in the recent state, but is nearest the A. 

 Tankeri'illci Swainson, from the Antilles. This is a much broader and larger 

 species. The A. siinilis Sowerby from North Australia is more like it, but the 

 proportions are different. It is named in honor of Mr. James Shepard, of New 

 Britain, Conn., to whom we are indebted for specimens. 



Family MARGINELLID^. 

 Genus MARGINELLA Lamarck. 

 Marginella ballista n. s. 

 Plate 4, figure 6. 

 Shell large, strong, rounded, subpyriform ; whorls about four ; spire short, 

 nearly enclosed by the last whorl ; sides convex, compressed about the mid- 

 dle near the adult varix ; outer lip thick, differentiated by a sulcus behind it, 

 arcuate in the direction of the whorl and also toward the body-lip, aperture 

 rather wide, especially in front ; body-wall with a callus which extends over 

 the spire from the posterior commissure; anteriorly with four rather oblique 

 plaits; outer lip smooth within. Max. Ion. of shell 18.0; lat. 11. 7; Ion. of 

 aperture 16.2 mm. 



Tampa silex-beds at Ballast Point. 



This has a peculiarly rounded form and thickened outer lip, which last has 

 no denticulations within. 



Marginella (ballista var. ?) tampae Dall. 



This form differs from the last by having straighter sides and therefore 

 more conical form, being wider at the shoulder and having a more elevated 

 and acute spire ; the two posterior plaits are stronger, less oblique and more 

 widely separated from the anterior pair and from each other. Lon. of shell 

 19.0; of aperture 16.5 ; max. lat. of shell 12.5 mm. 



Tampa silex-beds. 



This form, which more specimens might show to have specific value, re- 

 sembles Nelson's figure of M. incrassata from the Tertiary of Peru (Trans. 

 Conn. Acad. II., plate vi. figs. 5, 6), but has a higher spire, one more plait, does 

 not flare so much at the anterior end, which is also more attenuated, while the 

 outer lip is decidedly thicker. 



Marginella precursor n. s. 

 Plate 5, figure 4. 



Shell stout, solid, five-whorled ; original color dark brown or amber, with 

 numerous large, sharply defined, irregular-shaped, close-set spots of a much 

 lighter color, probably white, all over the surface ; form attenuated in front ; 

 sides somewhat convex, with little or no central compression behind tlie varix 



