56 
CORRELATION OF GEOLOGICAL FAUNAS. 
[BULL. 210. 
Table II. — Tropidoleptus fauna: Fourteen species occurring most frequently in 
the Hamilton formation of Cayuga Lake. 
[Dominant range frequency list for Cayuga Lake meridian.] 
Num- 
ber of 
zones 
in 
which 
found. 
Num- 
ber of 
zones 
in 
which 
found. 
1. Tropidoleptus carinatus 
2. Ambocoelia timbonata 
3 Palseoneilo constricta . 
21 
21 
21 
20 
20 
20 
19 
8. Chonetes mucronatus . . . 
9. Athyris spiriferoides 
10. Nuculites triqueter ... 
1 1 . Modiella pygma?a - 
18 
17 
17 
4. Spirifer pennatus 
5. Phacops rana 
6. Cryphaeus boothi 
7 Nucula corbuliformis 
16 
12. Tellinopsis subemarginata . . - 
13. Stropheodonta perplana 
14. Nuculites oblongatus 
16 
16 
16 
The list here compiled (Table II) exhibits the 14 species occurring 
most frequently in the 25 zones into which the formation was divided 
at Cayuga Lake exposures. It will be noticed that these 14 species 
occur in 16 or more of the 25 zones, and that 6 of them occur in 20 or 
more of the 25 zones. The first 5 in the list are also in the list of 12 
characteristic species of the eastern Hamilton (Table I, p. 51). These 
are Tropidoleptus carinatus, Ambocoelia umbonata, Palwoneilo con- 
stricta, Spirifer (mucronatus) pennatus, and Phacops rana; the 
remaining 7 of the dominant list are found in the Cayuga Lake sec- 
tion, but they are not among the more widel} r ranging species of that 
section. 
Chonetes coronatus is represented in 13 of the zones, in both the 
lowest and highest, and is fairly common in several of the zones in 
which it appears. 
Xucula bellistriata does not appear in the 6 lower zones at Cayuga 
Lake, but is seen in 8 of the zones above. 
Cryphaus boothi, which appears in 20 of the 25 zones of the Cayuga 
Lake section, is not common in the eastern sections. It was discov- 
ered in several sections about Smyrna and Sherburne, once at Sum- 
mit, and from Kingston southward the species is again occasionally 
reported, 13 times out of 36 stations. 
Chonetes mucronatus is among the long-ranging species of Cayuga 
Lake. It is fairly common in the eastern faunas, but not among the 
first 12. 
ModieTta pygmcea and Stropheodonta perplana are long-ranging 
species in the formation, and are frequent in the localities as far as 
Chenango Valley, and again from Kingston southward, but are rare 
in the intermediate region. 
Tellinopsis subemarginata and Nuculites oblongatus are frequently 
noted in the zones at Cayuga Lake, and are also fairly common east- 
ward, but fail to appear in the first 12 of the typical list. 
Looking over the range of the species in the zones of the Hamilton 
