Maryland Geological Survey 499 



derosa zone, Mortoniceras subzone, Perry and Dallas counties, Alabama. 

 Transition Beds, Eutaw to Selma. Dallas County, Alabama. Ripley For- 

 mation. Exogyra costata zone, Chickasaw and Union counties, Missis- 

 sippi. Selma Chalk. Exogyra ponderosa zone, east-central Mississippi. 

 Selma Chalk. Exogyra costata zone, Wilcox County, Alabama; east- 

 central Mississippi. 



Genus POLYNICES Montfort 

 [Conch., vol. ii, 1810, p. 222] 



Type. — Nerita mammilla Linne. 



The shell characters of Polynices are very similar to those of Natica; 

 it differs, however, in the possession of a corneous, rather than a calcareous 

 operculum. The genus, though of later origin than Natica, is much more 

 abundantly represented in the middle and late Tertiaries and in the East 

 Coast waters of to-day, and constitutes, indeed, one of the most con- 

 spicuous elements of the univalve faunas of eastern North America. 



Subgenus EUSPIRA Agassiz 

 [Sowerby, Min. Conch., German ed., 1842, p. 140] 



Polynices (Euspira) halli (Gabb) 



Plate XIII, Figs. 1, 2 



Lunatia halli Gabb, 1860, Jour. Acad. Nat. Sci., Phila., 2d ser., vol. iv, p. 



391, pi. lxviii, fig. 11. 

 Lunatia halli Meek, 1864, Check List Inv. Fossils, N. A., Cret. and Jur., 



p. 20. 

 Lunatia halli Conrad, 1868, Cook's Geol. of New Jersey, p. 729. 

 Lunatia halli Whitfield, 1892, Mon. U. S. Geol. Survey, vol. xviii, p. 130, 



pi. xv, figs. 13-16. 

 Lunatia halli Johnson, 1905, Proc. Acad. Nat. Sci., Phila., p. 21. 

 Lunatia halli Weller, 1907, Rept. Cret. Pal. New Jersey, vol. iv, p. 677, pi. 



lxxvi, figs. 11-14 (synonymy and figs. 9, 10, 15-19 excluded). 



Description. — " Elongated, subglobose, spire high ; whorls five, rounded 

 and angulated above; mouth elliptical, umbilicus open; surface smooth 

 or minutely wrinkled." — Gabb, 1860. 



Type Locality. — New Jersey. 



Etymology: Polynices, a son of CEIdipus. 



