430 Williams — Fossil Faunas and their use in 



The species of the Waverly fauna, collected and identified by 

 Dr. Kindle, are as follows, viz : 



1462 

 .p ♦ Tropidoleptus faunule as a colony in Chemung formation, 



Waverly, N. Y. 1462 B, (IT. S. G. S.,) identified by E. M. 



Kindle (1902). 



1. Tropidoleptus carinatus a Hamilton 



2. Ambocoelia umbonata a Marcellus-Chemung 



3. Phipidomella vanuxemi c Cornif.-Hamilton 



4. Spirif'er marcyi c Hamilton 



5. Vypricardella bellistriata c Hamilton 



6. Productella lachrymosa c Chemung 

 1. Delthyris mesaco stalls c Ith. -Chemung 



8. Camarotoechia contracta r Portage- Waverly 



9. Schizophoria cf. tioga rr Portage-Chemung 



10. Leptodesma matheri rr Chemung 



11. Glyptodesma erectum rr Hamilton 



12. Pterinopecten sp. rr 



13. P. crenico status rr Chemung 



14. Modiomorphacf.concentrica rr Hamilton 



15. Cyrtina hamiltonensis rr Up. Held., Ham., Ptg., Chem. 



The commonly reported range by formations is given in the 

 column on the right. 



In this faunule, it will be observed, the abundant and 

 common forms are, with the exception of Productella, chiefly 

 found in the Hamilton formation. 



Nevertheless the faunule occurs in the rocks after the 

 Spirifer disjunctns fauna has occupied the region in force with 

 its typical development ; thus showing that in time the two 

 faunas were coexistent in separate areas in their normal bionic 

 strength. That is to say, in the areas of their geographic 

 metropolis, each fauna maintains its bionic equilibrium as 

 expressed in frequency and dominance of species. 



The importance of this case of recurrence of the Tropido- 

 leptus fauna is so great as to call for every precaution as to its 

 verity. The intrinsic evidence of its Chemung horizon was 

 not present in the Owego faunule. There are no species there 

 which might not occur as low as the Ithaca Group. But the 

 faunule collected at Waverly contains Delthyris mesacostalis 

 with a distinctly strong median septum, which is wanting or 

 very slightly developed in the specimens of the Ithaca forma- 

 tion ; also a single specimen of Schizophoria tioga, nothing like 

 which is known in the typical fauna of the Ithaca formation. 

 The Productella lachrymosa is not so strongly of the true 

 lachrymosa type as to make it certain that it may not be an 

 extreme variation of Productella speciosa. The Leptodesmas 



