time none of these specimens were found in the preceding 
groups, and this was supposed to be a sufficient reason for 
making the upper layersa new division. A more diligent 
search, however, shows that these fossils also occur, al- 
though sparingly, in the other groups; since this is so, 
and as the line of division between the groups is not dis- 
tinct, they have very properly been designated as one 
group. In some places these upper layers contain courses 
of very good limestone. This is true of the western part 
of our county. For instance, in Marcellus this limestone 
is often quarried and used for building purposes; occa- 
sionally it is burnt for lime, although the product obtained 
is not very pure. 
The Corniferous Limestone and the Seneca, also, if we 
persist in retaining this subdivision, may be studied at the 
following places: just east of Manlius Village, south of 
Jamesville, and at the quarries north of Onondaga Hill, 
north of Skaneateles Falls, and south of Marcellus. 
Unless otherwise indicated, the following fossils are 
found throughout this entire period. 
PORIFERA. 
Petra Spongia, a small globular sponge about the size 
of an ordinarymarble. Abundant in the shaly layer over- 
lying the Onondaga. 
COELENTERATA. 
‘In several places this formation consists almost entirely 
of ancient coral reefs. There are several species of corals 
found in it. Stag-horn and cup corals are the most 
abundant. Aelophyllum Halli is a common variety. 
Favosites, or honey-comb coral, is also quite common. 
The most abundant species are the Favosites Goldfussi and 
I. Gothlandicus. 
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