228 SYSTEMATIC PALEONTOLOGY 



ridges or teeth, the lower one of which is the most distinct. The surface 

 of the shell has been polished when perfect." 



There is little doubt that it is the same as the Maryland form. The 

 identity of Emmons' species is a different question. 



Length, 9 mm. ; diameter, 6 mm. 



Occurrence. — Calvert Formation. Plum Point. 



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

 Cornell University. 



Family CERITHIOPSID/E. 



Genus SEILA A. Adams. 



Seila adamsii (H. C. Lea). 



Plate LV, Fig. 6. 



Cerithium Emersonii var. C. B. Adams, 1839, Boston Jour. Nat. Hist., vol. ii, p. 285. 

 Cerithium terehrale C. B. Adams, 1840, Boston Jour. Nat. Hist., voL iii, p. 320, 



pi. iii, fig. 7. 

 ? Cerithium clavubm H. C. Lea, LS43, New Fossil Shells from the Tertiary of Virginia 



(Abst.), p. IL 

 Cerithium Adamsii H. C. Lea, 1845, Trans. Amer. Philos. Soc, vol. ix, p. 268. 

 Cerithium annulatum Emmons, 1858, Rept. N. Car. Geol. Survey, p. 269, fig. 161. 

 Cerithiopsis annulatum Conrad, 1863, Proc. Acad. Nat. Sci. Phila., vol. xiv, p. 566. 

 Cerithiopsis annulatum Meek, 1864, Miocene Check List, Smith. Misc. Coll. (183). 



p. 17. 

 Seila Adamsii Dall, 1892, Trans. Wagner Free Inst. Sci., vol. iii, pt. ii, p. 267. 



Description. — " Granules obsolete, with simj^le, broad, elevated, revolv- 

 ing lines, the middle one on several of the lower whorls as prominent 

 as the outer ones." Adams, 1839. 



" Shell small, elongated, brown, frequently with a white band, with 

 rather slight incremental strife; whorls eleven or twelve, flattened: spire 

 seven-eighths of the length of the shell, five-sixths of its bulk, its opposite 

 sides containing an angle of about 20°, conic, with four elevated, obtuse, 

 revolving lines on each whorl, of which the first and second, and third 

 and fourth are equidistant; the space between the second and third is 

 obviously less on the upper whorls, but approaches to an equality with the 

 other spaces, in the growth of the shell; the first three ridges are equal, 

 and the fourth small and depressed, so as to lie almost wholly beneath 

 the first of the succeeding whorl; the suture consequently appears on the 



