30 A CONTRIBUTIOX TO THE LoWER DeVOXIAX FaUXAS OF MaRYLAXD 



Description. — " Shell obliquely siibovate or subglobose, somewhat 

 graduall}' expanclmg, and becoming ventricose in the last volution. Spire 

 composed of about four volutions, which are contiguous except the last one 

 near the aperture, the apex being nearly in the jilane of the outer volution : 

 aperture expanded, campanulate, and sometimes with the lip reflexed. 

 Surface marked by fine transverse undulating stria?, which are sometimes 

 distinctly bent backwards along a line near the dorso-lateral curvature of 

 the shell, or nearer to the middle of the summit, and rarely slightly 

 carinated along this line. In a few specimens, distinct revolving striae 

 are seen cancellating the transverse stria?." Hall, 1859. 



This is the most common species of gastropod in the Lower Devonian 

 of the state. It varies widely in size and in the character of the apex 

 which is sometimes above and sometimes below the plane of the body 

 whorl. See further remarks under var. vcntricosum. 



Occurrence. — Oriskaxy Formation, Bidgely Member. Knobly 

 Mountain, Monster Rock, opposite Keyser, West Virginia; Nicholas 

 Mountain, Hancock, Cumberland, Flintstone, Maryland; Warren Point, 

 Pennsylvania. Helderberg Formatiox, JSTew Scotlaxd Member. 

 Cumberland, Maryland; Cherry Eun, Miller's Spring, West Virginia; 

 Warren Point, Pennsylvania. 



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



Platy'ceras gebhardi var, vex'^tricosum Conrad 

 Plate LXXXl 



Platyceras ventricosuvi Conrad, 1S40, Ann. Rept. Pal. N. Y., p. 206. 

 Platyceras ventricosum Hall, 1859, Nat. Hist. N. Y., Pal., vol. ill, p. 311, pi. 



ivi, figs. 1-4, 8; pi. Ivii, fig. 4; p. 475, pi. cxviii, figs. 3-9, 1861. 

 Platyceras ventricosum Meek and Worthen, 1868, Geol. Survey 111., vol. lii, 



p. 441, pi. ii, figs. 4a, h. 

 Platyceras ventricosum Nicholson, 1874, Rept. upon the Pal. of the Province 



of Ontario, p. 115, pi. ii, figs. 1, 1«. 

 Platyceras ventricosum Nettleroth, 1889, Kentucky Fossil Shells, p. 168, pi. 



XXV, fig. 10. 



Description. — " Shell ventricose; aperture very large and campanulate; 

 volutions three, contiguous, depressed below the upper margin of the 

 whorl." Conrad, 1845. 



