374 
Tlic American Geologist. 
Dt'c-ember, 1901 
101' 
101' 
Base of exposed seetioii. D.-ilinnnclln miiltisectfi. 
PIcctnmboiiites sericcus. (No. 3). 
Level of Ohio river at Vevav. 
5: 5j - b 
The correspondences between these two sections are too 
apparent to need further emphasis. Numbers 3 to 49 of the 
Vevay section have an aggregate thickness of approximately 
96 feet. The same zones in the Cincinnati section have an ag- 
gregate thickness of about 100 feet. Trinuclcns' concentriciis 
oomes in at ahiiost exactly the same level in 1)oth sections. 
Nuniljcr 63 of the Vevay section is probably to be correlated 
with the 260 foot level of the Cincinnati section and number 
45 with the 180 foot level of the latter. Number 73 is not 
the equivalent of Ulrich's 180 foot level. ConstcUaria constel- 
lata ranges through a considerable thickness of rocks. 
Numbers a to h of the Vevay section seem to be equivalent 
to all above the 285 foot level of the Cincinnati section ; thougli 
the unexposed portions of the Vevay section may conceal a 
zone of Hoinotrypa cnrvata between numbers 55 and 83. Cer- 
tain it is that this well characterized species occurs abundantly 
in zone a, though not above it. If it is true that these Hoino- 
trypa zones are equivalent, then the beds XII a of Ulrich's sec- 
tion are to a large degree suppressed in the Vevay section. 
It remains to discuss certain peculiarities in the range of 
several species. 
CaUopora onealli sigillaroides occurs in the lowest layers as 
a very small form and increases in size but without alteration 
of internal characters as higher layers are reached passing 
apparently into the variety connnunis of James, a form occur- 
ring in large masses and prodigious numbers in some of the 
higher zones. 
DckaycUa nlrichi seems to experience a similar progressive 
increase in size the variety robiisfa occurring in beds well up in 
the series. 
DahnancUa inidtisccta occurs in nearly every limestone 
layer up to the base of the Platystrophia zone; and numbers 3 
to 61 inclusive may witli great propriety be called the Daliuan- 
clla multisccta zone. Where this species occurs abundantly the 
