the preceding, with a smoother surface. Both are ex- 
tremely abundant, and are found at all the localities men- 
tioned. 
Merista sulcata. Not as common as the preceding. 
Found at Britton’s Quarry. 
LAMELLIBRANCHS. 
Pterinea rugosa. This specimen is quite abundant, be- 
ing found at nearly all the quarries mentioned. 
Avicila communis and Azicula umbonata are two 
lamellibranchs that are rarely met with in our county. 
‘They are found in the lower layers. 
CRUSTACEANS. 
Eurypterus remipes represents a new family that makes 
its appearance with this period. It is quite abundant in 
some of the counties east of us, but we have the only 
known specimen that has as yet been found in our county. 
As this fossil is found in similar layers of the Waterlime 
Group to the east and to the west of us, it is reasonable to 
suppose that it exists somewhere in the rocks of this for- 
mation in our county. The specimen mentioned was 
picked up amid some loose material and drift in Onondaga 
Valley, and it is possible that it may have drifted in from 
one of the adjoining counties. 
Lederditia alta is another crustacean found in this 
period. It is an ostracoid, and very abundant. Speci- 
mens a fourth of an inch in length are not rare. Dana 
says of it, ‘‘ The Lederditza alta of this period is unusually 
large for its family, modern ostracoids seldom exceeding 
a twelfth of an inch in length.” 
This period may be advantageously studied at the fol- 
lowing places: 
(1) Dorwin Springs, (2) Split Rock, (3) Britton’s, (4) 
Hibbard’s, (5) Russell’s Quarries, the three latter being on 
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