398 Systematic Paleontology 



Type Locality. — Owl Creek, Tippah County, Mississippi. 



Shell ovate to subcylindrical in outline ; height of aperture more than 

 one-half the total altitude ; whorls five or six in number, minutely tabu- 

 lated, feebly inflated, increasing in size with a moderate degree of rapidity ; 

 external surface sculptured with fine, regularly spaced, squarely chan- 

 nelled, linear sulci, seven or eight in number upon the penultima, and 

 between twenty-five and thirty on the body ; inter-areas low and flattened, 

 more than double the width of the sulci; fortuitous secondary spirals 

 developed midway between the primaries on the medial portion of the 

 ultima ; sulci microscopically punctated by the incrementals ; suture lines 

 distinct, impressed; body whorl evenly rounded at the base; aperture 

 rather narrow; outer lip almost vertical, patulous anteriorly; inner lip 

 constricted at the base of the ultima; columella reinforced near its 

 extremity and bearing a single very oblique plication, which almost or 

 quite evanesces before reaching the aperture ; parietal wall entirely free 

 from callous. 



Dimensions (figured specimen). — Altitude 14 mm., maximum diam- 

 eter 5.7 mm. 



The Maryland species is quite certainly identical with Conrad's Solidu- 

 lus linteus from the Ripley of Tippah County, in spite of the dissimilarity 

 in the two figures. Conrad's figure is a reconstruction made from a badly 

 crushed individual with the aid of his imagination, and is inaccurate in 

 the relative proportions of spire and body whorl and in the outline of the 

 aperture. 



Occurrence. — Monmouth Formation. Brightseat, Prince George's 

 County. 



Collection. — Maryland Geological Survey. 



Outside Distribution. — Ripley Formation. Exogyra costata zone, Owl 

 Creek, Tippah County, Mississippi. 



Acteon gabbana Whitfield 



Actcronina Mplicata Gabb, 1861, Proc. Acad. Nat. Sci., Phila., 1860, p. 93, pi. 



ii, fig. 13. (Not Actaon Mplicata d'Orbigny.) 

 Actwon Mplicata Meek, 1876, Hayden, Rept. U. S. Geol. Survey, Terr., vol. 



ix, pp. 281, 282. 



