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dences of the identity of these deposits. Through the kindness 

 of Mr. K. Giliiss, a resident of the neighborhood, he has recently 

 obtained specimens which are conclusive on this point. As in 

 nearly all the other localities, these fossils occur in a dark and 

 somewhat bituminous slate, between the thin laminse of which 

 they are very closely crowded. They are evidently identical 

 with those found in the Chesterfield coal measures, and the other 

 Middle Secondary districts of North Carolina, Virginia, and 

 Pennsylvania, referred to in former communications. 



The Bannister tract lies in a direction south by west, and at 

 a distance of about 45 miles from the localities in Cumberland 

 and Prince Edward Counties, where the Posidonomya was first 

 discovered in association with characteristic plants of the Chester- 

 field coal measures. It is placed, therefore, in the line of the 

 Mesozoic rocks in Virginia, and serves more nearly to connect 

 this with the Eastern or Deep River Belt of North Carolina. 

 The rocks of this group, near the centre of Prince Edward 

 County, form an oval outlying patch, less than a mile in diameter, 

 not far from the southern end of the principal belt, and there are 

 indications of one or more similar outliers between this and the 

 Bannister. These facts, in connection with the topography of 

 the intervening country, favor the opinion that this middle belt 

 was once continuous as far as the southern boundary of Virginia, 

 beyond which it may have united with the prolonged tract which 

 includes the Deep River deposits of North Carolina. 



Prof. William B. Rogers next communicated some observations, 

 made within the past year, in regard to the metamorphic influ- 

 ence of Trappean rocks on the adjacent sedimentary strata, and 

 exhibited a series of specimens from Prince William County, 

 Virginia, illustrating these phenomena. The tract whence the 

 specimens were taken is part of the great belt, extending contin- 

 uously from New Jersey far into Virginia, which has commonly 

 been designated as of the New Red Sandstone or Trias, but 

 which Prof. Rogers, on the evidence of fossils, has more recently 

 inferred to be closely allied to the rocks of the Eastern and Mid- 

 dle belts of Virginia, and therefore, in a geological position, 

 somewhere about the base of the Jurassic series. The shales 

 and sandstones of tHis region are intersected by numerous dykes 



