138 SYSTEMATIC PALEONTOLOGY 



Subclass STREPTONEURA. 

 Order CTENOBRANCHIATA. 



Suborder ORTHODONTA. 



Superfamily TOXOGLOSSA. 

 Family TEREBRID/E. 



Genus TEREBRA Adanson. 



Terebea unilineata Conrad. 

 Plate XL, Figs. 1-2. 



Cerithium unilineatum Conrad, 1841, Amer. Jour. Sci., voL xli, p. 345, pi. ii, tig. 4. 

 Verithium unilineatum Conrad, 1843, Trans. Assoc. Amer. Geo!, and Nat., p. 108, 



pL V, fig. 4. 

 Acus unilineata Tuomey and Holmes, 1856, Pleiocene Fossils of South Carolina, 



p. 137, pi. xxviii, fig. 7. 

 Terebra unilineata Emmons, 1858, Rept. N. Car. Geol. Survey, p. 258, fig. 129. 

 Terebra (Acns) unilineata Conrad, 1863, Proc. Acad. Nat. Sci. Phila., vol. xiv, p. 565. 



Description. — "Slightly turrited; volutions with each a spiral im- 

 pressed line above the middle; space between this line and suture with 

 oblique plicEe." Conrad, 18-il. 



" Shell thick, elongate bands alternate, acute, tapering gradually to a 

 point ; whirls many, seventeen or eighteen, and ornamented by revolving 

 impressed lines, and passing just above the middle of the whirl; the 

 upper jjart of the spire is also marked by short longitudinal ribs, which 

 are interrupted by spiral lines. Oblique lines of growth are usually 

 conspicuous. In old specimens, the ribs are obsolete." Emmons, 1858. 



The body whorl of Emmons' figured specimen is proportionately longer 

 than indicated in his figure. 



We have a single fragment, the body whorl and part of the next. The 

 sculpture is somewhat obsolete. 



Length of fragment, 22 mm. ; diameter, 13 mm. 



Occurrence. — Calvert Formation. Plum Point. 



Collection. — Maryland Geological Survey. 



