74 CORRELATION OF GEOLOGICAL FAUNAS. [bull. 210. 
plete and thorough an analysis of the faunal contents of the Ithaca 
formation as we have of the Hamilton formation in Mr. Grabau's 
analysis of Eighteenmile Creek, or in Dr. Cleland's analysis of the 
Cayuga Lake section. In both of the latter cases the rocks are exposed 
in continuous sections from bottom to top, and each zone is open for 
inspection over considerable horizontal space. Nevertheless, Dr. 
Kindle's analysis of the faunal contents of the Ithaca formation is 
more complete than anything else published, and it presents statistics 
from which a fair idea of the bionic values of the species composing 
the faunas may be estimated. 
The dominant species of the fauna are the following, the figures 
indicating the frequency of occurrence of the species in the 54 fau- 
nules analyzed : 
Table XIII. — Productella speciosa fauna: Dominant species of the Ithaca 
formation at Ithaca, N. Y. 
1 . Spirifer pennatus var. posterns 3a 
2. Productella speciosa 25 
3. Modiomorpha subalata var. chemungensis . . 25 
4. Chonetes scitulus 24 
5. Cyrtina hamiltonensis 23 
6. Palaeoneilo filosa 21 
7. Camarotcechia eximia and stephani 21 
8. Atrypa reticularis 20 
9. Stropheodonta mucronata 19 
10. Actinopteria boydi 19 
11. Pleurotomaria capillaria 19 
12. Stictopora meeki 17 
13. Palaeoneilo constricta . . 17 
14. Cypricardella bellistriata 15 
15. Spirifer mesistrialis 14 
16. Leiorhynchus mesicostale . . 14 
17. Grammysia subarcuata 14 
18. Orthoceras bebryx var. cayuga 14 
19. Ambocoelia umbonata. _ 13 
This maybe considered as a standard list of the fauna of the Ithaca 
formation. Three points must be noted, however: (1) Several char- 
acterisUc species of the Ithaca formation are not in this list, because 
they do not occur as frequently as all these other species; (2) a large 
proportion of this standard list is made up of common Hamilton spe- 
cies (i. e., species of the standard Tropidoleptus carina! us fauna); 
(3) the species which are peculiar and dominant are closely related 
to species of the Tropidoleptus carinatus fauna. It will be noticed, 
however, that not a single one of the dominant species of the Tropi- 
doleptus carinatus fauna appears until we reach the thirteenth species 
in this list; and among these 19 dominant species of the typical 
Ithaca formation only two species of the dominant Tropidoleptus 
fauna are present, i. e., Palaioneilo constricta and Ambocoelia umbo- 
nata. 
