EXPLANATION OF PLATES. 
Fig. 20, Amphidiscus rotula of Ehrenberg, probably derived from a Spongilli. Fossil at 
West-Point, near Boston, Wrentham, &;c., also in South America. 
21 to 23. Siliceous bodies of organic origin, found with fossil fresh-water infusoria. 
24. Dictyocha fibula ? Ehr. Common among fossil marine infusoria in the infusorial 
stratum of Virginia at Richmond and Rappahannock cliffs. 
25. Fragment of the preceding. 
26. Dictyocha speculum, Ehr., with the preceding. 
27 and 28. Siliceous bodies, found with the preceding. 
29. Binary, triangular, siliceous bodies, found with the preceding. 
30 to 35. Siliceous spicula, etc. probably derived from marine sponges or Actinia, found 
with the preceding. 
36. Scale showing yVoths of a millimetre, magnified equally with the drawings. 
PLATE XLIV. 
Fig. 1. Section from Monticello, Sullivan county, to the Croton river, near Bull’s bridge, in 
Westchester county. 
2. Section from Forestburgh, Sullivan county, across Orange and Rockland counties to 
Tarry town, Westchester county. 
3. Section from Oneonta, on the Susquehannah, to Jones’s Beach, Long island, across 
Delaware, Sullivan, Orange, Rockland, Westchester, and Queens counties. 
PLATE XLV. 
View of the entrance of Howe’s cave, in Schoharie county. 
PLATE XLVI. 
Fig. 1. Section from Roxbury, Delaware county, to the Connecticut line (Vide line of sec¬ 
tion on the State map). 
2. Section from Fallsburgh, Sullivan county, by the mouth of Murderer’s creek, across 
Orange, Putnam, and Westchester counties, to the State line. 
3. Section from the Catskill mountains, in Neversink, across Ulster, Dutchess, and Put¬ 
nam counties, to the State line. 
