MARYLAND GEOLOGICAL SURVEY 237 



TURRITELLA VARIABILIS VAR. ALTICOSTATA Conracl. 



Plate LVII, Fig. 2. 



Turritella aUlcostata Conrad, 1834, Jour. Acad. Nat. Sci. Phila., voL vii, 1st ser., p. 144. 



Turritdla alticostata Conrad, 1863, Proc. Acad. Nat. Sci. Phila., vol. xiv, p. .'567. 



Turritella terebriformis Harris, 1893, Amer. Jour. Sci., ser. iii, vol. xlv, p. 30. 



Turritella terebriformis Ball, 1892, Trans. Wagner Free Inst. Sci., vol. iii, pt. ii, p. 

 311 (in part). 



Description.—" Shell much elongated, subulate, whorls twelve to four- 

 teen, each profoundly carinated near the base, and with prominent spiral 

 striae." Conrad, 1834. 



This variety includes those forms from the Choptank formation which 

 are characterized by the presence of very large revolving ribs on the lower 

 half of the whorl. This condition was well developed only on the later 

 whorls of large individuals.' 



Length, unknown; diameter, 21 mm. 



Occurrence. — Choptank Formation. Greensboro, Dover Bridge, 

 Peach Blossom Greek, Cordova, Flag Pond, Governor Eun, 2 miles south 

 of Governor Run, Pawpaw Point. 



Collections.— llaryland. Geological Survey, Johns Hopkins University, 

 U. S. National Museum. 



Turritella variabilis var. cumberlandia Conrad. 

 Plate LVII, Figs. 3, 4. 



Turritella variabilis var. Conrad, 1880, Jour. Acad. Nat. Sci. Phila., vol. vi, 1st ser., 



p. 331. 

 Turritella Cumberlandia Conrad, 1863, Proc. Acad. Nat. Sci. Phila., vol. xiv, pp. 



567, 584. 

 Turritella cumberlandia Meek, 1864, Miocene Check List, Smith. Misc. Coll. (183), 



p. 16. 

 Turritella cumberlandia Whitfield, 1894, Mon. xxiv, U. S. Geol. Survey, p. 139, pi. 



xxiii, figs. 9-11. 



Description. — "Elongated, tapering gradually: volutions 24, bicari- 

 nated, carinje nearly equal, distant ; revolving lines unequal, wrinkled : 

 sides of whorls concave between the carinse, somewhat channeled beneath 

 the lower one, and rounded at the base. Length 2f ." Conrad, 1862. 



1 Dr. Dall referred to his T. terebriformis si)ecimens from the Chipola beds, from the 

 Miocene of Virginia (collected by Conrad) and Harris' specimen from Greensboro (not 

 Torktown, Va.). The last is identical with alticostata. The species terebriformis may 

 still be valid if the Maryland specimens are eliminated. 



