156 BRUCE CLARK 
belonging to that epoch of deposition. A very large percentage of 
the species are common to the Meganos of the Coalinga section, 
as well as to that of the Mount Diablo region." 
Correlation.—It was from these Eocene beds in Ventura County 
that convincing evidence was first obtained that the Meganos 
belongs to the same horizon as that of the Eocene of Marysville 
Buttes and Table Mountain near Oroville, California, the beds 
of which localities contain the fauna of the Siphonalia sutterensis 
zone. The large number of highly ornamented species common 
to the Meganos of the Ventura County region and to the Eocene 
of these other localities seems to show conclusively that we are 
dealing with beds that are nearly, if not exactly, contemporaneous. 
One of the localities, from which the writer has obtained the 
best-preserved Meganos fauna in the Ventura County area, is 
along Aliso Canyon about four miles northeast of the east end 
of Simi Valley. Here were found a number of the species which 
have been regarded as characteristic of the Siphonalia sutterensis 
zone. The following quotation is taken from the published 
abstract of one of Dickerson’s papers in which he refers to this 
section: 
A year ago Mr. Reginald Stoner discovered a locality in the Santa Susana 
Mountains, on Aliso Canyon of Devil Creek, just beneath the Miocene strata. 
The fossils from this locality represent a lower phase of the Siphonalia sutter- 
ensis zone and the fauna is essentially the same as the Siphonalia sutterensis 
zone of the Roseburg Quadrangle, on Little River near the confluence with 
the Umpqua. 
In the Simi Hills, a few miles away from the locality discovered by Mr. 
Stoner, the Rimella simplex zone of the middle Tejon stage occurs; the general 
absence of this zone through most of the Coast Range region is probably due to 
extensive erosion during the interval between upper Eocene and Oligocene time. 
Dickerson, at the time the above-mentioned paper was written, 
supposed that these beds containing the fauna which he recognized 
t For the list of the described species from the Meganos of the area under discussion 
the reader is referred to the list on pages 158-59. 
2 R. E. Dickerson, ‘‘Occurrence of the Siphonalia Sutterensis Zone, the Uppermost 
Tejon Horizon in the Outer Coast Ranges of California,” Bull. Geol. Soc. America, 
Vol. XXIX (1917), p. 163. 
