MARYLAND GEOLOGICAL SURVEY 151 



111 aihlitidii l(j thu ty])e we have only a crushed Naiica from Wood- 

 stock thai may represent this species. 



Length, 10 mm.; width 12 mm. 



Occurrence. — Naxjemoy' Formation. Woodstnck. (?) Aquia For- 

 mation. Clifton Beach. 



Collections. — Maryland Geological Survey, Johns Hopkins University. 



Genus LUNATIA Gray. 



Lunatia marylandica Conrad. 



Plate XXVIII, Figs. 2, 2a, 3. 



Lunatia marylandica Conrad, 1865, Amer. Jour. Couch., vol. i. pp. 2(5, 211, pi. xxi, 



tig. 11. 

 Lunatia marijla7idica Clark, 1895, Jobus Hopkius Univ. Circ, vol. xv, p. 4. 

 Lunatia inanjlandica Clark, 1806, Bull. 141, U. S. Geol. Survej', p. 09, pi. xii, tiirs 



3a— oc. 

 cf. Xatica cminula var. Harris, 1809, Bull. Amer. Pal., No. 11, p. 88, pi. xi, fig. 22. 



Description. — " Suborbicular or subovate, Yolutions 5; spire short, 

 whorls convex, subcontracted below the suture; labium with a callus on 

 the upper part, reflected over the umbilical margin; umbilicus moderate 

 in outline, j^rofound, showing most of the volutions." Conrad, 18G5. 



The stratigraphic and geographic range of this species is very great. 

 It is larger, however, and more abundant in the lower beds of the Aquia 

 formation. The affinities of the species are with L. eminula (Conrad) 

 of Alabama, especially with L. eminula var. Harris, of the Alabama 

 Chickasawan, which is an intermediate member of a series of which the 

 Claibornian L. eminula and L. marylandica are end members. 



The separation of these species is very difficult, and possibly all the 

 forms ought to be referred to L. eminula which is the older name. The 

 Maryland forms show almost, if not quite, the complete range of varia- 

 tion of the series. 



Length, 32 mm.; width, 30 mm. 



Occurrence. — ISTanjemot Formation. East and west of Port Tobacco, 

 Woodstock. Aquia Formation. 1 mile northeast of Piseataway, Po- 

 tomac Creek, 2 miles below Potomac Creek, Upper Marlboro, Liverpool 

 Point, Mouth of Paspotansa Creek, Aquia Creek, 1 mile southeast of 

 Mason Springs, Gtymont, Hardesty, Fort Washington. 



