204 Systematic Paleontology — Middle Devonian 



Wood has reported the same species from the Stafford limestone in the 

 Marcellus shale of Erie Connty, N. Y., stating that a thin bed of lime- 

 stone is largely composed of shells of this species and Strophalosia 

 truncata (X. Y. State Museum, Bull. 49. 1901, p. 145, and see p. 165 for 

 description together with figures 21-23 of pi. 9). The surface of this 

 species, however, differs strikingly from that of A. virginiana in being 

 spinous as indicated by the numerous elongated pits, the shell is also con- 

 siderably larger, the average dimensions being given as length 5.3-6 mm. 

 and width 7.2-7.9 mm. ; while the dorsal valve is marked by a shallow 

 sinus instead of a low fold with a sinus on each side toward the front as 

 in the latter species. 



Occasionally in some of the iron' stained shales are small flattened 

 specimens of Ambocoelia, which apparently belong to this species. The 

 most numerous specimens of this species seen by the writer occur in a 

 ciit on the Eomney branch of the B. & 0. E. E. between Green Spring and 

 Springfield, about three miles south of Green Spring, W. A^a. At this 

 locality is a thin, very dark gray limestone containing large numbers of 

 this species, and they are also abundant in some of the associated brown- 

 ish shales. This outcrop is in the Marcellus shales of the Eomney for- 

 mation.^ 



Length, 1| mm. ; width 2 mm. 



Occurrence. — Eomney Formation. Marcellus Member. One mile 

 east of OldtoMTi; three miles south of Green Spring, W. Va. Hamilton 

 Member. East bank Evitts Creek below Wolfe Mill ; W. Va. side Potomac 

 Eiver, li/. miles below Cumberland. 



Collection. — Maryland Geological Survey. 



Ambocoelia praeumbona Hall ( ?) 



Plate XX, Figs. 7, 8 



Ortliis praeum'bona Hall, 1857, Tenth Rep. N. Y. State Cab. Nat. Hist., p. 167. 

 Ambocoelia praeumbona Hall, 1860, Thirteenth Rep. N. Y. State Cab. Nat. 



Hist., p. 71. 

 Ambocoelia praeumbona Hall, 1807, Pal. N. Y., vol. iv, p. 2G2, pi. xliv, figs. 1-6. 

 Ambocoelia praeumbona Schuchert, 1S97, Bull. U. S. Geol. Surv., No. 87, p. 



141. 



' The specimen figured from south of Green Spring was sent to Kindle who 

 wrote that it was probably a new species. 



