52 CORRELATION OF GEOLOGICAL FAUNAS. [bull. 210. 
The total number of species cited in faunule lists from 140 localities, 
divisible into 30 groups of localities, in eastern New York and Penn- 
sylvania is 172. In addition to these positive identifications, 15 
species are named with a query, and 11 genera not positively identi- 
fied by species are cited. From these statements the lists must be 
regarded as approximate, not perfect, lists of the species of the fauna. 
We must await further investigations to perfect the conclusions 
drawn from them, which can be only outlined at the present time. 
DISTRIBUTIONAL VALUES OF THE SPECIES. 
In the first column, after the name of the species in Table I, is given 
the number of times each species is recorded in the 140 localities. In 
the second column the localities are grouped by fives, making 30 
groups in all, and the number of such groups of localities in which 
the species occurs is given. 
Analysis of these two sets of statistics shows that the 12 species of 
the list have all been reported from 32 or more of the 140 localities, 
nearly 22 per cent of the whole. When the distribution is based on 
groups of five localities the frequency readies 17 out of 30 times, or 
nearly 59 per cent, showing that we have for all of them a common 
distribution, which would place them in 50 per cent or more of the 
localities examined in a cursory survey of the regions studied. 
The best 6 of the list show a frequency of occurrence equal to 
nearly a third of the localities examined, and the same species all 
occur in as man}" as 23 of the 30 groups of five, and the best 5 out of 
the 12 occur in 26 out of 30, or nearly 90 per cent of the cases. It is 
safe to assume, therefore, that the first 12 species of this list give a 
fair representation of the dominant fauna of the Hamilton formation 
as it is expressed in eastern New York and Pennsylvania. 
FREQUENCY VALUES OF THE SPECIES. 
The dominance of the species in the fauna may be proved by noting 
the number of times each species is reported as abundant or common- 
in the local faunule in which it occurs. This kind of value may be 
called the frequency value of the species in the particular faunule. 
The facts for this test are given in the third and fourth columns; the 
figures in the third column express the number of times the species is 
recorded as abundant, and those in the fourth column the number of 
times the species is reported as common. We note at once the promi- 
nence of the first four species of the list. 
The first species is cited as abundant 20 times and common 33 times; 
or for 59 times out of the 113 records it is at least common. This spe- 
cies is Spirifer (mueronatus) pennatus of Atwater. 
The second species in the list, Tropidoleptus carinatus, is abundant 
22 times and common 30 times; or 52 times it is a common constituent 
of the fauna. 
