424 Williams — Fossil Faunas and their use in 



have yielded 35 separate zones, of which the faunules have 

 been accurately noted. 



The number of species in the first set of statistics is 172 ; in 

 the second 234 ; and in the third 163. In the first set of sta- 

 tistics the geographically dominant species are ascertained. A 

 list of 12 species is derived which are reported from over 32 

 of the 146 localities examined — the five more dominant ones 

 are from over 50 of the 146 localities. When the localities are 

 grouped in 5's lying most nearly together, so as to eliminate 

 the imperfection of the collecting, the best 5 of the 12 species 

 occur in 26 out of 30 of these groups of localities ; and all the 

 12 species of the dominant list occur in 17 out of the 30 

 groups. The evidence is clear that we have in such a list the 

 species which possessed the highest bionic value in distribu- 

 tion. 



The list in order of dominance is as follows : 



A BCD 



1. Spirifer pennatus (Atw.) _„. 113 30 26 33 



2. Tropidoleptus carinatus 89 27 22 30 



3. Spirifer granulosus 59 28 11 15 



4. Chonetes coronata. 57 26 10 16 



5. Palseoneilo constricta _ 56 27 2 5 



6. Nucula bellistriata 42 23 4 8 



7. Amboccelia umbonata 40 22 4 8 



8. Nuculites triqueter 38 22 17 



9. N. oblongatus 35 ' 21 1 3 



10. Nucula corbuliformis 33 17 4 3 



11. Athyris spiriferoides 32 24 2 5 



12. Phacops rana _ _ 32 18 14 



A — number of times in the 146 faunules ; 



B — number of times in 30 groups of 5 faunules each ; 

 C — number of times marked abundant (a), and 

 D — number of times marked common (c). 



The figures in the columns to the right signify that the first four 

 species of the list are decidedly the more abundant in indi- 

 viduals, in the faunules, as shown by the figures in the fourth 

 and fifth columns. This list, then, gives us the expression of 

 bionic dominance in distribution and frequency in the faunas 

 of eastern New York and Pennsylvania. 



The analysis of the Cayuga Lake and Eighteen Mile Creek 

 faunules will give the range-bionic values. Fourteen species out 

 of the 234 were found to be dominant in being the more fre- 

 quently represented (all of them 16 or more times) in the 25 

 successive zones ; 9 of this list are also in the dominant list, 

 based on geographical distribution and frequency in the 

 eastern area. 



Analysis of the Eighteen Mile Creek statistics shows that 

 there is a list of 12 species which are in 14 or more of the 35 



