A Contribution to the Loaver Devonian Faunas of Maryland 25 



Occurrence. — Helderberg Formation. East of Martin Mountain, 

 Allegany County, on road leading to lUish. 

 Collection. — Maryland Geological Survey. 



Class GASTROPODA 



Subclass STREPTONEURA 

 Order ASPIDOBRANCHIA 



Suborder RHIPIDOGLOSSA 

 Family PLEUROTOMARIDAE 



Genus PLEUROTOMARIA Defrance 



Pleurotomaria labrosa Hall 

 Plate LXXX, Fig. 1 



Pleurotomaria lahrosa Hall, 1859, Nat. Hist. N. Y., Pal., vol. ill, p. 339, pi. 

 Ixvi, figs. 1-5; pi. Ivii, figs. 6a, &, 1861. 



Description. — " Shell rhomboid ovate. Spire little elevated above the 

 body of the shell: volutions three or four; the upper ones small and 

 moderately increasing, the last one ventricose, much expanded on the 

 outer side, and subangular: aperture broadly ovate; the columellar lip 

 extremely thickened, the callosity extending to the outer lip. Surface 

 marked by prominent spiral ridges with wider furrows between, and, on 

 the upper part of the volution, by a broader band or groove, which is mar- 

 gined by carinas: lines of growth marked by strong elevated lamellose 

 striae, which are undulated in passing over the spiral ridges ; those mark- 

 ing the broader spiral band are less strongly elevated, and make a single 

 retral curve, indicating the marginal sinus.'' Hall, 1859. 



Occurrence. — Helderberg Formation, jSTew Scotland ]\Iember. 

 Cumberland. 



Collection. — Georo-e M. Eoeder. 



