634 EDWARD M. KINDLE 



bly lived in deeper waters. That the two faunas were limited to their 

 respective areas solely by marine conditions, such as ocean currents, 

 or differences in depth or temperature, is indicated by the frequent 

 interleaving and intermingling of the faunas in sections located near 

 the general boundary between the two faunal provinces. The two 

 Nunda sections nearest the Altoona section which have been studied 

 in Pennsylvania are the Catawissa and Hollowing Run sections, 

 located at the Susquehanna River, to the northeast of Altoona. Com- 

 parison of the Nunda faunas of the Susquehanna and the Altoona 

 sections shows that they represent respectively the eastern and western 

 facies of the formation. The dominance of the Ithaca fauna is as 

 complete in the Susquehanna sections^ as is that of the western fauna, 

 in the Altoona section. That the Altoona section is more remote 

 from the old shore-line of the Nunda sea than the Susquehanna sec- 

 tions is indicated by their respective geographic positions as well as 

 by their faunas. The Altoona section is located just at the Allegheny 

 front, while the Susquehanna sections lie well to the southeast of it. 

 Chemung fauna. — No very sharp line can be drawn on a litho- 

 logic basis between the Nunda and the Chemung. The faunas, how- 

 ever, are very distinct, as the following list of the Chemung species 

 indicates : 



Orhiculoidea doria Leiorhynciis mesacostale 



Stropheodonta mucronata Stropheodonta cj. demissa 



Spirijer disjunctus Strohpeodonta perplana var. nervosa 



Schizophoria striatula Chonetes scitula 



Orthotheies (Schuchertella) Productella cj. hallana 



chemungensis Leptodesma protextum 



Atrypa hystrix Leptodesma lichas 



Airy pa reticularis Leptodesma sp. 



Delthyris mesacostalis Pterinea cf. dispanda 



Dalmanella tioga Loxonema terebra 



Productella lachrymosa Edmondia sp. 



Productella cj. speciosa Schizodus pauper 



Spirijer mesastrialis Modiomorpha subalata var. 



Camarotoechia contractavar. chemungensis 



Camarotoechia sappho Stenaster sp. 



Ambocoelia gregaria 



I The faunas of these sections are listed in Bulletin No. 244, U. S. Geological 

 Survey, pp. 78, 91. 



