Maryland Gkological Survey 471 



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 tlie apex 

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

 See further remarks nndcr var. veniricosiim. 



Occurrence. — Oriskany Formation, Ridgely Member. Knobly 

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

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

 Pennsylvania. HeldehbiiRG Formation, New Scotland Member. 

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

 Warren Point, Pennsylvania. 



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



[Ohern.] 



Platyceras gebhardi var. ventricosum Conrad 



Plate LXXXI 



Platyceras ventricosum Conrad, 1840, Ann. Rept. Pal. N. Y., p. 206. 

 Platyceras ventricosum Hall, 1859, Nat. Hist. N. Y., Pal., vol. iii, 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. iii, 



p. 441, pi. ii, figs. 4a, 6. 

 Platyceras ventricosum Nicholson, 1874, P.ept. upon the Pal. of the Province 



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

 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. 



" The shell is obliquely ovate spreading rapidly from the apex, and be- 

 coming extremely ventricose below ; aperture campanulate ; the lip in con- 

 tact with the spire, and sometimes strongly refiexed. Surface marked by 

 fine transverse or concentric lamellose striae, which are somewhat un- 

 dulated and rarely finely cancellated by faint, revolving stri«. Volutions 

 contiguous throughout, or the last one free ; peristome continuous or in- 

 terrupted, free or in contact with the body volutions, sometimes abruptly 

 expanded at the margin." Hall, 1859. 



