Maryland Geological Survey 549 



Avicula linguwformis Meek, 1859, Hind's Rept. Assiniboia and Saskatche- 

 wan Expl. Exped., p. 1S3, pi. i, fig. 7. 



Pterin linguifonnis Meek, 1864, Check List Inv. Fossils N. A., Cret. and 

 Jur., p. 9. 



Pteria petrosa Meek, 1864, Check List Inv. Fossils N. A., Cret. and Jur., 

 p. 9. 



Pteria linguifonnis Meek, 1876, Rept. U. S. Geol. Survey Terr., vol. ix, 

 p. 32, pi. xvi, figs. la-Id. 



Pteria linguifonnis White, 1879, 11th Ann Rept. U. S. Geol. and Geog. Sur- 

 vey, Territories, pp. ISO, 197, 205. 



Pteria linguifonnis Whitfield, 18S0, Geol. Black Hills ot Dakota, p. 384, pi. 

 vii, figs. 2, 3. 



Pteria linguiformis Whitfield, 1885, Contributions Canadian Pal., vol. i, pt. 

 i, p. 31. 



Pteria petrosa Whitfield, 1885, Mon. XJ. S. Geol. Survey, vol. ix, p. 68, pi. 

 xiv, fig. 10. 



Pteria petrosa Weller. 1907, Geol. Survey of New Jersey, Pal., vol. iv, p. 429, 

 pi. xlii,, figs. 1, 2. 



Description. — " Subquadrangular, very oblique, ventricose; anterior 

 hinge extremity sharply angulated; anterior margin obliquely subtrun- 

 cated interiorly; posterior extremity subangulated." — Conrad, 1853. 



Type Locality. — Chesapeake and Delaware Canal, Delaware. 



The species is represented in Maryland only by a single distorted cast, 

 which has probably been correctly referred to this species. The form is 

 an unusually interesting one, because of its occurrence in the Fort Pierre 

 and Fox Hills group of the western interior and because of the presence 

 of closely allied forms in the Cretaceous of southern India. 



Occurrence. — Monmouth Formation". Bohemia Mills, Cecil County. 



Collections. — Maryland Geological Surrey, Xew Jersey Geological Sur- 

 vey, IT. S. National Museum. 



Outside Distribution. — Magothy Formation. Cliffwood clay, New 

 Jersey. Matawan Formation. Wenonah sand, New Jersey. Black Creek 

 Formation. North and South Carolina. Ripley Formation. Exogyra 

 costata zone, Alcorn County, Mississippi. Pierre Shales. "Western Interior. 



Pteria ehojibiga n. sp. 

 Plate XXI, Fig. 11 ; Plate XXII, Figs. 1-3 

 Description. — Shell rather heavy, nacreous, laminar in texture, rhora- 

 boidal in outline, inflated along a broad ridge extending obliquely back- 



