082 Systk-maxic Paleoxtology — Upper Devonian 



OlITIiOXYCIIIA UXGUICULATA 11. Sp. 



Plate LXX, Figs. 7-9 



Descripiioii. — Shell conical, curved ; apex niiniite, incurved; volutions 

 about one and onc-lialf. Initial portion of shell often somewhat com- 

 pressed laterally or even carinate; body volution expanding towards 

 aperture, bearing folds of varying degrees of distinctness. The extent 

 to which the folds are developed is variable, in some specimens being 

 scarcely noticeable, in others pronounced. Apei'ture subcircular or 

 slightly compressed laterally, oblique, fluted by folds in some shells. 



Length of specimen of ordinary size 10-13 mm. ; diameter of aperture 

 6-8 mm. This species differs from Platyceras marylandicum in its more 

 attenuate apex and smaller size. 



Occiiirence. — Jennings Formation, Parkhead Member. Williams 

 Eoad, on Polish ^Nfountain, 1660 common; 21,4 miles above mouth of 

 Sideling Hill Creek. 



Collection. — Maryland Geological Survey. 



Orthonyciiia sp. 

 Plate LXX, Figs. 10, 11 



Description. — A single specimen in the Parkhead fauna differs from 

 the other species observed in increasing less rapidly in diameter toward 

 apex. It resembles 0. vngiiiculata but the apex is less attenuate and 

 aperture more plicate than is usual in that species. It resembles Platycera>< 

 manjlandicwm in its plications but increases much less rapidly in diam- 

 eter, a feature not well shown in the drawings. Larger collections may 

 prove it to be a new species. 



Length 12 mm. ; diameter aperture 7 mm. 



Occurrence. — Jennings Formation, PAiiKHEAo Member. Two and 

 one-half miles above mouth of Sideling Hill Creek. 



Collect ion. — ]Mar viand Geolooical Survev. 



