prosser] TULLY LIMESTONE OF CENTRAL NEW YORK. 7 
After describing the locality from which the above species were col- 
lected, 'Prof. White said: "There can be little doubt that this stratum 
represents the Tully limestone horizon of the New York Beports, and it 
thus becomes a valuable guide in correlating and classifying the rocks 
of the district." 1 
Again, the same exposure is described more fully under the geology 
of Stroud Township, where the professor states that the rock is " per- 
forated in every direction with the holes left from the removal of corals 
and other calcareous remains by solution. 
" Fossil shells are very abundant, Spirifer, Tropidoleptus, and Avicula 
being very numerous, while crinoidal fragments also abound." 2 
The Pennsylvania horizon under consideration is usually a calcareous 
shale, instead of a massive limestone, and does not lithologically resem- 
ble the Tully limestone of central New York. But far more important 
than its lithologic character is the fact that in this horizon the species 
which are especially characteristic of the Tully limestone are absent, 
while those of the Hamilton constitute its fauna. 
While considering the correlation of this zone it is well to take into 
account the known eastern extension of the Tully limestone of central 
New York. The farthest east Vanuxein found this formation was in 
Chenango County, " at the northwestern part of Smyrna, on the road to 
De Ruyter village, where the road crosses the west branch of the Che- 
nango." :! 
Prof. Emmons in 1846 discussed the absence of the Tully limestone 
in eastern New York, and I see no reason for dissent from his views. 
He said: "The Hamilton shales, however, are limited above, or superi- 
orly, by a dark-colored mass which has been called the Tully limestone. 
This would seem a sufficiently distinct limit if the limestone extended 
eastward j but as it is absent in the river counties, and scarcely extends 
beyond the central counties in this direction, the group is still left 
without a distinct line of demarcation in nearly one-half of the State. 
We are therefore obliged to resort to a careful study of its fossils in 
order to define the limits which the mass occupies." 4 Also "in Albany 
and Schoharie counties it [Tully limestone] is unknown." 5 
In the summer of 1886 the writer studied this region, and near Upper- 
ville, in Smyrna Township, reported limestone layers 25 feet in thick- 
ness separated by calcareous shales. 6 Prof. S. G. Williams reports 
this same locality as " the easternmost poini at which I have found 
anything answering to the Tully." 7 Finally, Prof. H. S. Williams 
says: "The Tully limestone is a zone of argillaceous limestone ranging 
'G6, p. 109. 
: 0p. cit., p. 271. 
sGeol. New York, Pt. Ill, 1842, p. 292; also, see p. 164. 
4 Agriculture of New York, Vol. I, p. 183. 
6 Ibid., p. 186. 
6 Proc Am. Asso. Adv. Science, Vol. XXXVI, 1887, p. 210. 
'Sixth Ami. Rept. State Geol. [New York], 1887, p. 18, also see map on " Geographical distribution 
of the Tully limestone m central New York," accompanyiHg the paper. 
