EXPLANATION OF THE PLATES. 
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Fig. 1. 
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Fig. 1. 
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6 . 
!>fluviatile, recent and fossil. 
a, h, Navicula sigma ? marine, Stonington. 
a, h. Navicula-, fossil at Richmond, Virginia. 
a, b, c. Eunotia arcus, fluviatile, recent and fossil, c, cross section. 
a, b, c. Eunotia-, brackish ditches, New-Jersey. c, cross section. 
Eunotia monodon, 
Eunotia diodon, 
Eunotia triodon, 
Eunotia tetraodon, 
Eunotia pentodon^, 
Eunotia serra, 
Cocconeis-, marine, Florida. 
Bacillaria paradona, marine, Hudson river, 
a, b. Bacillaria tabellaris, ] 
a, b. Bacillaria tabellaris, full grown ? J 
Bacillaria-, marine, at Stonington, Connecticut. Recent. 
Tessella catena ? marine, at Stonington, Connecticut. Recent. 
Fragillaria pectinalis, ] 
Fragillaria bipunctata ? ] 
a, b. Meridion vernale, fluviatile recent and fossil in fragments. 
fluviatile, recent and fossil. 
[ fluviatile, recent and fossil. 
PLATE XXIII. 
Hudson slate and Taconic rocks. 
Section of the Indian-pond ore bed. 
Section of the Amenia ore bed, Dutchess county. 
Section at Leedsville mountain, Amenia. 
Section of the Ancram lead mine, Columbia county. 
Section of Bockee’s and Bryan’s lead mines, Dutchess county. 
Lateral dislocations of limestone, Ghent, Columbia county. 
Section south of Redrock, Columbia county, a and b. Interstratifications of slate 
and quartz, c. Slate permeated by quartz. 
Section of the Stuyvesant quarries, Columbia county. 
PLATE XXIV. 
Hudson slate and Helderberg limestone. 
Contortion of slaty grits : Rogers’s island, Columbia county. 
Contorted strata at Great Neutenhook, Columbia county. 
Section of various rocks at Great Neutenhook. 
Slight faults in limestone of Becraft’s mountain, Columbia county. 
Section at the southeast part of Becraft’s mountain. 
Section at the same place, shewing the limestone and Hudson slate. 
