32 A COXTRIBUTIOX TO THE LoWER DEVONIAN FaUNAS OF MARYLAND 



Plattceras subfalcatum n. sp. 

 Plate LXXXII, Figs. 7, 8 ; Plate LXXXIII, Figs. 1-3 



Description. — Shell subfalcate; whorls (of casts) one; very rapidly ex- 

 panding from beak to aperture, becoming extremely ventricose, and sud- 

 denly contracting at the aperture ; surface marked by low, distant, parallel, 

 longitudinal undulations, sometimes becomes slightly nodulose; aperture 

 subcircular; outer surface and peristome not seen. Found only as internal 

 casts. 



This species in the character of the undulations, bears some resemblance 

 to P. platystomum of the Lower Helderberg of New York; but its shape 

 and the constriction of the aperture show it to be distinct from other 

 species of the genus. 



Diameter of shell 4.5 cm. to 8 cm.; of aperture 3.2 cm. to 6 cm. 



Occwrrence.— Oriskany Formation^ Eidgely Member. Hancock. 



Collection. — Maryland Geological Survey. 



Platyceras patulum Hall 

 Plate LXXXIII, Fig. 4 



Platyceras reflexiun Hall, 1859, Nat. Hist. N. Y., Pal., vol. Hi, p. 477, pi. cxx, 

 fig. 3, 1861. 



Description. — " Shell subhemispheric. Spire forming about three \olu- 

 tions, which are usually contiguous, sometimes free, very rapidly expand- 

 ing, the last one extremely ventricose and assuming a hemispheric form; 

 apex much below the plane of the last volution. Aperture nearly circular ; 

 peristome much expanded upon the side of the body volution, and thicken- 

 ing below in the form of a columellar lip. Surface transversely striated." 

 Hall, 1859. 



Occurrence. — Oriskany Formation, Eidgely Member. Cumberland. 



Collection. — Frank Hartley. 



Platyceras reflexum Hall 

 Plate LXXXIII, Figs. 5, 6 ; Plate LXXXIV, Figs. 1, 2 



Platyceras reflexum Hall, 1859, Nat. Hist. N. Y., Pal., vol. iii, p. 477, pi. cxx, 

 figs. 1-7, 1861. 



