JUNE 7, 1912] 
No deposits in any way similar to those of 
the Eocene of this northeastern region have 
so far been observed south of Abasola, which 
is 120 miles north of Tampico. The last 
characteristic Gulf Coast Eocene fossils were 
found on the Presas river 160 miles north of 
Tampico. 
In the region to the south and west of 
Tampico an entirely different condition ex- 
ists. The Papagallos shale continues along 
the western border of the lowland and also 
occurs as inliers in the later formations. It is 
a compact blue shale, more or less calcareous, 
and up to the present we have found no fossils 
in it. 
Tt is succeeded by a shale so similar in color 
and general structure as to make a separation 
extremely difficult, unless one is fortunate 
enough to find the fossils which occur here 
and there in it. One such locality is that on 
the Buenavista River near Alazan, some 25 
miles northwest of Tuxpam and 75 miles 
south of Tampico. <A collection of fossils 
made at this point by Professor Cummins 
shows a fauna consisting principally of small 
gasteropods with a few bivalves, many of 
which are very similar to, and some identical 
with, those of the Tejon beds of the Pacific 
coast. More detailed examinations will doubt- 
less result in recognizing these beds at many 
other localities, since they unquestionably 
underlie a large area. They may even extend 
northward through the valley in which the 
Tampico and Monterey railroad runs, since we 
found similar fossils in a well at Topila at a 
depth of 1,810 feet. From this locality we 
have the following forms as determined by 
Mr. G. C. Gester: 
. Dentalium stramimewm Gabb. 
. Surcula monolifera. 
. Turris n. sp. (near but not Claytonensis). 
. Olivella near-mathewsonit. 
. Corbula (species not determined but identical 
with a specimen from Marysville Buttes 
Tejon). 
6. Tritonium (Murex) un. sp. (identical with ma- 
terial from Marysville Buttes Tejon). 
7. Conus remondit. 
Oo wm w DD He 
SCIENCE 
907 
8. Neverita secta or Lunatia horniit (Gabb). 
9. Neverita secta var. 
10. Tritonium sp. (identical with specimen from 
Marysville Buttes). 
11. Turris n. sp. 
12. Turritella. 
13. Cerithium. 
14. Hulima? 
15. Acteon? 
Out of the fifteen species here enumerated, 
five are identical with Tejon species and six 
others are very closely related to them. 
Not only are the fossils of this area of Pa- 
cifie coast types but the sediments are similar 
to those of that area and entirely different 
from those of the Texas region. 
These Alazan shales are overlain directly by 
the yellow clays of the San Fernando, which 
are well exposed both west of the Buena- 
vista River near Alazan and eastward between 
Solis and Meson. Large quantities of fossils 
are found, including Orbitoides papyrycea, 
echinoderms, pectens and many species of 
this as yet unstudied fauna. These yellow 
clays and sands are the surface material over 
a large portion of the coast country between 
Tuxpam and Tampico and its fossils were 
found at a number of places in this area. It 
is succeeded by beds of similar composition 
but later age, which are found only in a nar- 
row belt along the coast itself. 
It appears that from the beginning of the 
Oligocene to the Pliocene there was compara- 
tively little change in the character of the 
sediments, yellow clays and sands making up 
the bulk of the deposits. The difference of 
age is, however, marked by change in faunas 
and the San Fernando is succeeded by the 
Tuxpam Miocene, whieh we found near La — 
Loma. 
The time equivalency of the Tejon and 
Claiborne being probable, we find here appar- 
ently contemporaneous deposition of the At- 
lantie and Pacific types of middle Kocene 
along what is now the same Gulf coast within 
a comparatively short distance of each other. 
While we have not yet had time to study the 
Tamaulipas range with this idea in view, it 
appears probable that it may represent a part 
