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[Assembly 
gypseous deposit, which embraces the great masses quarried for plas- 
ter, the hopper shaped cavities," the vermicular limerock" of Eaton, 
and other porous rocks ; and 4th, those rocks which abound in groups of 
needle form cavities, originally occupied by sulphate of magnesia. 
Not a fossil has been observed in the two lowest deposits ; they are 
found, but rarely, in the two upper ones. In the 3d mass at Bull's quar- 
ry we find a few small fucoides, resembling spear grass, the Lingula 
limosa and two or three thin shelled bivalves not yet determined. A 
small Cytherina in the road from Jordan to Peru, on the south side of 
the canal. Two species of bivalves are also found at Dunlop's mill, be- 
low Jamesville, accompanied by fucoides and a large sized Cytherina, 
all occurring in a coarse calcareous slate, and I should judge makes a 
part of the mass which encloses the plaster, being between the upper 
and lower beds. It is in this slate that I should place the Eurypterus 
remipes. It has not yet been found within the plaster region, but in 
the series of the plaster region, below Waterville, and in a rock or mass 
which extends east through the district, having a gypseous shale below 
it, and the Manlius water lime series above it. 
Manlius water lime group. This group embraces all the beds of 
water lime south of the Erie canal, which are burnt for cement. It is 
very constant in its character, and I have traced it from Cayuga lake 
to the hills in the rear of Hudson. It affords the most profitable lime- 
stone for burning of the whole series of limestone rocks, and from this 
cause it is always chosen when present, requiring less wood to calcine 
a given measure than the other limestones. From Cayuga to Hudson 
river, kilns are arranged by the sides or upon the top of this rock. 
This group is admirably characterized by its fossils, and before 
these were well known, its blue limestone was often confounded with 
the Trenton limestone. Its layers are dark blue and drab ; the latter 
furnish the water lime, the former the caustic lime. Its fossils are 
Atypa plicata, Pterinea , Stenoscisma bisulcata, Littorina peran- 
tiqua, Cytherina , Leptaene punctulifera ? Teotaculites, 6cc. &c. 
At the bottom of this group, or top of the last, we find the Catenipora 
labyrinthica. 
Pentamerus Limestone. This limestone comes in from the first dis- 
trict as a thick mass, and with numerous fossils as to individuals, but 
runs out before reaching Onondago valley, its fossil disappearing in 
