62 
CORRELATION OF GEOLOGICAL FAUNAS. 
[BULL,. 210. 
disappearance of the Tropidoleptus fauna from the eastern corner of 
the basin. 
On following these faunas westward it is found that the Tropido- 
leptus fauna lies entirely below the Genesee shale in the Genesee 
Valley and farther westward. The formations called Sherburne, 
Ithaca, Oneonta, and, I am inclined to think, a considerable part of 
what is classified as Chemung in the eastern half of the State, lying 
above the Oneonta, must be regarded, on stratigraphical grounds, as 
equivalent to the Portage formation of the Genesee Valley. 
EFFECT OF ADDITIONAL STATISTICS. 
In order to demonstrate the way in which such a standard list as 
Table V is affected by additional statistics, a few cases are left for 
analysis after the estimate has been deliberately made. 
The faunules of the Unadilla region of Otsego and Delaware coun- 
ties, in eastern New York, were gathered by Prof. C. S. Prosser and 
reported in 1893. a In his report 37 faunules are analyzed and the 
species tabulated. The number of species positively determined is 
66; 18 more species are named, but marked with a query, and 13 gen- 
eric names are cited without identification of the species observed. 
The 12 more common species of the 37 faunules are named in 
Table VI. 
of the Hamilton formation 
Table VI. — Tropidoleptus fauna: Dominant 
of the Unadilla region. 
* 1 . Ambocoelia umbonata . 23 
*2. Tropidoleptus carinatus .. 20 
Spirifer pennatus 17 
Paracyclas lirata 11 
Leiorhynchus laura _ . 10 
* 6. Nuculites oblongatus 13 
*3 
4 
5 
7. N. triqueter 9 
8. Chonetes coronatus 9 
9. Spirifer granulosus ._ . 7 
10. Palaeoneilo constricta 7 
11. Spirifer medialis 7 
12. Chonetes scitulus 7 
species belong to the standard 
It will be noted that 8 of these 12 
dominant list of 12 (Table V), compiled from the various statistics of 
the State. They are marked with asterisks before the names. 
The species of the standard list which are not among the first 12 
species of the Unadilla list are — 
Phacops rana. 
Athyris spiriferoides. 
Nucula corbulif oralis . 
N. bellistriata. 
The dominant list for the Unadilla district contains four species not 
in the general dominant list, which are — 
Paracyclas lirata. 
Leiorhynchns laura. 
Spirifer medialis. 
Chonetes scitulus. 
a Forty-sixth Ann. Rept. New York State Museum, 1893, pp. 256-288. 
