1883.] blO [Lesley. 



But the fact must be kept in view, that no interval of time can elapse 

 between emergence and resubmergence, without the interval being ac- 

 cented by erosion which has gone on during the interval. If the time 

 interval in question extended through the Catskill era, Michigan standing 

 above sea level, there should not only be a plane of paleontological non- 

 conformity, but also nonconformable bedding ; and, in soft Devonian 

 measures, this would be deeply sculptured. None such being known in 

 Michigan, we must conclude that the time-interval was spent under 

 water ; but in that case sedimentation must have gone on. We are there- 

 fore shut up to the conclusion that several thousand feet of Perry County, 

 Pennsylvania, deposits are represented by a few yards, feet, or perhaps 

 only inches of Michigan rocks ; yet nevertheless perfectly and conforma- 

 bly represented. 



Early Records of the Society. 



Mr. Lesley, in reporting the completion of his MS. Con- 

 densed Copy of the Minutes of the Society, upon which be 

 has been engaged, at intervals, during the last two years, 

 said : 



These Minutes, preserved in ten volumes, commence with Franklin's 

 letter of 1744, and reach to the last meeting in December, 1837, after which 

 the Proceedings were regularly printed for the use of the members, at first 

 four times, and then twice a year, the first issue of 1838 being numbered 1, 

 and {he last issue of 1882, 112. 



Vol. I, 1838, 1839, 1840, contains Nos. 1 to 14. 



Vol. II, 1841'3, contains Nos. 15 to 26. 



Vol. Ill, Celebration of the Hundredth Anniversary, No. 27. 



PROC. AMER. PHILOS. SOC. XX. 113. 4g. PRINTED MAT 25, 1883. 



