98 
BULLETIN OF THE LABORATORIES 
geologists of Ohio grew out of the attempt to construe certain local 
thickenings of the conglomerates of the Waverly. These we explain 
tentatively as deposits at the mouth of rivers and, in conformity to 
this theory, trace them as narrow bands of a tortuous character, ex- 
tending, for example, north-westward from east Licking to west Knox 
and Richland counties. Wherever such disturbing factors enter, one 
seeks in vain for familiar landmarks, but a very few miles on either 
side reveals the well-remembered sequence. The term “Waverly 
conglomerate” of the Ohio geologists stands merely for such local de- 
velopments and the admission of this element, often with the remainder 
of the series as seen near by, or occasionally without it, produces the 
most abnormal variations in the general sections. 
This fact by no means depreciates the labors of the geologists in 
question, it was an unavoidable incident to the plan necessarily fol- 
lowed. Notwithstanding, for many purposes, just that opportunity to 
determine the relative position of a stratum in one part of the state 
with another in a distant county, is of greatest practical and theoretical 
importance. 
Before beginning such a discussion as the present one it is well 
to have clearly defined the ruling principles upon which the investiga- 
tion is based, we therefore premise the following : 
Geological Aphorisms. 
1. Palaeontological determinations, to possess the highest value, 
must be accompanied by minute vertical and acurate geographical 
data. 
2. Lithological determinations in sedimentary rocks are only 
valuable in connection with detailed palaeontological and orographical 
study. 
3. It must be remembered that the palaeontological study of a 
single section, no matter how complete, gives no opportunity for the 
tracing of the genesis or history of a species. At most it gives only a 
series of disconnected instantaneous photographs of the species as it 
was at widely separated’ times under very diverse conditions. 
4. To study the phylogeny of a group it will be necessary to fol- 
lows it in its migrations as it continually seeks to preserve constant the 
fluctuating bathymetric conditions. 
5. Strata of similar lithological character, even if separated by a 
considerable vertical interval, may more closely resemble each other 
