THE EURYPTERIDA OF NEW YORK 9 
engaged in acquiring these fossils and when the work was done the rock 
exposure was left with a vertical face, so that no further product is now 
available. In this eastern region of New York State the Salina formation 
is without salt deposits but the Otisville basin doubtless antedated those 
deposits in central New York and is assignable to an early part of the 
Salina stage. 
Colony P, or the Pittsford pool, is embedded in a black shale formation 
which has never been exposed in any natural outcrops. As we have 
observed, the rock was first brought to light by excavations made in the 
deepening of the Erie canal in 1895 and the outcrops were soon after covered 
by the riprap construction of the canal lining and so remain. Extensive 
collections of material were made by Mr Clifton Sarle and these were 
subsequently increased by the work of Messrs D. D. Luther, H. C. Wardell 
and Fred. Braun. The opportunity of further acquisitions from this fauna 
rests with the future and depends on possible new excavations in the pro- 
gress of public improvements. 
Colony H, or the Herkimer pool, has been long exploited. It lies 
above the horizon of the salt and its localities are in the vicinity of Jeru- 
salem Hull, Clayville, Sauquoit and Waterville. The most productive parts 
of the region have been the Wheelock and Schooley farms near Jerusalem 
Hill, though here as elsewhere actual outcrops of the waterlime are few. 
Experience has shown that the exploitation of the fresh rock does not 
afford eurypterids in satisfactory preservation, because of its blue gray 
character. Exposure not only reduces this to a light gray but aids the 
fissility of the rock and the broad, flat surfaces of the fossils also help to 
induce cleavage planes in the matrix. Exposure of a few years to the 
weather aids but little. The experiment was made of taking from the out- 
crop a good many cords of fresh rock which were left exposed for a period 
of five years but the result in the particulars referred to was wholly 
unsatisfactory. Therefore the supply of these fossils has come from 
weathered slabs distributed over this region. Mules of stone fences have 
been inspected and many rods of them taken down and rebuilt. Some of 
