MARYLAND GEOLOGICAL SURVEY 147 



of the spire with one strong revolving rib in the center, with a secondary 

 one on each side of it, and several intermediate ones between; body 

 whorl with several ribs below those represented on the spire; notch on 

 the shoulder (central rib), and marked rugose lines of growth. 



Length (restored), 25 mm.; diameter, 8 mm. 



Occurrence. — Choptank Formation. Jones Wharf, Dover Bridge. 



Collection. — Maryland Geological Survey. 



Pleurotoma (Hemipleurotoma) communis Conrad. 

 Plate XLI, Pigs. 2, 3. 



Pleurotoma commmds Conrad, 1830, Jour. Acad. Nat. Sci. Pbila., vol. vi, 1st ser. p. 



224, pL ix, fig. 33. 

 Pleurotoma communis Conrad, 1842, Proc. Nat. lust., BulL ii, p. 186. 

 Pleurotoma communis Emmons, 1858, Kept. N. Car. Geol. Survey, p. 264. 

 Surcula communis Conrad, 1863, Proc. Acad. Nat. Sci. Phila., vol. xiv, p. 561. 

 Surcula communis Meek, 1864, Miocene Check List, Smith. Misc. Coll. (183), p. 21. 

 Pleurotoma communis Harris, 1893, Amer. Jour. Sci., ser. iii, vol. xlv, p. 28. 



Description.— " Shell subfusiform, smooth, with one obtuse carina 

 revolving in the middle of each whorl, except the last, which has three; 

 the lowest one obsolete ; beak attenuated and slightly recurved. 



"This is a numerous species of the locality at St. Mary's Kiver.'' 

 Conrad, 1830. 



The sides of each whorl are straight or nearly so, and the medial carina 

 is sharply elevated. The siphonal notch is not deep but is on the shoul- 

 der of the whorl. 



Length, 25 mm. ; diameter, 7 mm. 



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

 Langley's Bluff. 



Collections.— Maryland Geological Survey, Johns Hopkins L^niversity, 

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

 AVagner Free Institute of Science, Cornell University. 



Pleurotoma (Hemipleurotoma) communis var. protocommunis 



n. var. 



Plate XLI, Figs. 4, 5, 6. 

 Description.— Shell fusiform, elongate, of thick substance, uine- 

 whorled; spire high; body whorl short, beak attenuate, straight; whorls 



