172 SYSTEMATIC PALEONTOLOGY 



Marginella denticulata Conrad, 184o, Fossils of the Medial Tertiary, pt. iv, p. 86, 



pi. xlix, tig. 10. 

 Porcellana (Glabella) dentimlata Conrad, 1S63, Proc. Acad. Nat. Sci. Phila., vol. xiv, 



p. 564. 

 Marginella denticulata Meek, 1864, Mioc-ene Check List, Smith. Misc. Coll. (183), 



p. 19. 

 Marginella denticulata Dall, 1890, Trans. Wagner Free Inst. Sci., vol. iii, pt. i, 



p. 51, pi. V, tig. 8. 

 Marginella {Eratoidea) denticn.lala Cossmann, 1899, Essais de Paleoconch. Comp., 



vol. iii, p. 88. 



Description. — " Shell smooth, polished, spire conical; columella four 

 plaited, the three lower plaits ohlique; right lip denticulate within; 

 aperture rather more than half the length of the shell." Conrad, 1830. 



" Subovate, polished; spire conical; columella 4-plaited; labrum den- 

 ticulate within, straight, rather more than half the length of the shell."' 

 Conrad, 1845. 



Dr. Dall, in the paper referred to above, has discussed the synonomy 

 and characteristics of this species in great detail. 



Length, 6.5 mm. ; diameter, 3 mm. 



Occurrence. — St. Mary's roRMATiON. St. Mary's River. 



Collections. — Maryland Geological Survey, Johns Hopkins University, 

 Philadelphia Academy of iSTatural Sciences. 



Marginella calvertensis n. sp. 

 Plate XLIV, Fig. 6. 



Description. — Shell elongate, solid, surface highly polished, and with 

 faint longitudinal ribs; whorls about five; spire about the length of the 

 body whorl; whorls strongly convex, with a marked subsutural con- 

 striction which gives the spire a turreted appearance; inner lip with a 

 slight callus; outer lip thick and flaring; plates four, lower three very 

 oblique, the posterior the strongest and least oblique. 



Length, 10 mm. ; diameter, 4 mm. 



Occurrence. — Calvert Formation. Plum Point. 



Collections.- — Maryland Geological Survey, Johns Hopkins University, 

 U. S. National Museum. 



