MARYLAND GEOLOGICAL SURVEY 143 



This form is most closely related to T. curvilirata, from which it dif- 

 fers in lacking distinct subsutural tubercles and in possessing strong 

 spiral threading. 



Length, 22 mm. ; diameter, 5 mm. 



Occurrence. — St. Mary's Formation. St. Mary's Eiver. 



Collections. — Maryland Geological Survey, U. S. National Museum, 

 Wagner Free Institute of Science. 



Subgenus HASTULA H. & A. Adams. 



Terebra (Hastula) simplex Conrad. 

 Plate XL, Fig. 10. 



Terebra simplex Conrad, 1830, Jour. Acad. Nat. Sci. Phila., voL vi, 1st ser., p. 236, 



pi. ix, fig. 33. 

 Terebra simplex Conrad, 1843, Proc. Nat. Inst., BulL ii, pp. 185, 187. 

 Terebra simplex Conrad, 1863, Proc. Acad. Nat. Sci. Phila., vol. xiv, p. 565. 

 Terebra {Aem) simplex Meek, 1864, Miocene Check List, Smith. Misc. Coll. (183), 



p. 18. 

 Terebra (Subula) simplex Conrad, 1868, Amer. Jour. Conch., vol. iv, p. 68, pi. v, 



fig. 5. 

 Terebra simplex Harris, 1893, Amer. Jour. Sci., ser. iii, vol. xlv, p. 38. 

 Terebra simplex Dall, 1895, Proc. U. S. Nat. Museum, vol. xviii [No. 10351, p. 34. 



Description. — " Shell elongate conical, smooth, with plain undivided 

 whorls; sides straight; the lines of growth are very distinct, and the 

 large whorl slopes abruptly towards the base; the aperture is rather 

 large." Conrad, 1830. 



" Subulate ; volutions 10 to 12, sides nearly straight, slightly de- 

 pressed above the middle ; on the whorls toward the apex this depression 

 is more like an impressed line near the suture ; lines of growth distinct 

 and curved; body whorl rather abruptly rounded at base." Conrad, 

 1868. 



Length, 45 mm. ; diameter, 12 mm. 



Occurrence. — St. Mary's Formation. St. Mary's Eiver, Cove Point, 

 Langley's Bluff. 



Collections. — Maryland Geological Survey, Johns Hopkins University, 

 Philadelphia Academy of Natural Sciences, U. S. National Museum, 

 Wagner Free Institute of Science, Cornell University. 



