156 Annals of thk Carne(;ie Museum. 



Thf.dford Region. (Dominant Range Frequency List.) 



No. of Zones in 

 Species. Which Found. 



1. Spirifier ntncronatus, 5 



2. Priviilopsis punctilifera, 5 



3. StropheoJonta io'Maensis, 5 



4. Leiorhynchiis laicra, 4 



5. Chonetes lepida, 3 



6. Stropheodonta deiiiissa, 3 



7. Cytrina hamiltonensis, 3 



8. Stropheodonta perplana, 3 



9. .S. cpiicava, 3 



10. Athyris fiiltonensis, 2 



1 1 . Ceratopora intermedia, 2 



12. Favosites turbinata. 2 



Shinier and Grabau divide the section into six zones, and there is 

 no species reported which occurs in all. Three species occur in five 

 of the six, one in four, five in three, and there are three which occur 

 in only two. Of the twelve, nine are brachiopods, two corals and one 

 an ostracod, which illustates well the difference between the faunas 

 of the Avestern and eastern sections. In the distributional frequency 

 list for eastern New York there are six brachiopods, five pelecypods, 

 one trilobite and nov corals. As the list for eastern New York is a 

 distributional and not a range list, the writer has endeavored to con- 

 struct a list from Prosser's report, in the absence of a detailed section, 

 but the result is very un.satisfactory. The attempt, however, brings 

 out one ])oint. 



In Prosser's report, some of his sections are sufficiently long and 

 well enough located so that the approximate distance of the various 

 zones below the top of the formation is known. There are thirteen 

 such zones at different localities, which are located between i and 150 

 feet below the top of the Hamilton ; ten located 150 and 300 feet 

 below the top ; five located between 300 and 600 feet below the top ; 

 and two which are between 600 feet below the top of the Hamilton 

 and the top of the Marcellus. 



Then making a composite section with four zones, there can be 

 constructed a sort of a range frequency list, which is, however, of 

 little value, because the number of species reported below the 600 foot 

 level is very small. This list is as follows : 



