HILL: GEOLOGY OF THE ISTHMUS OF PANAMA. 271 
PART VI. 
Appendices. 
Rzgronr ву DR. WILLIAM Н. DALI, UPON THE PALEONTOLOGY OF 
THE COLLECTIONS.) 
I have examined the fossils from the Isthmus оҒ Panama and Costa 
Rica submitted by you, and now send you my conclusions. From the 
fauna and lithologic character the different horizons appear to be as 
follows : — 
A. Altered, partly recrystallized, limestone, (Nos. 14, 21, and 22, 
near Empire. Probably Tertiary, perhaps Еосепе. 
B. Shale with Orbitoides forbesii (No. 1). This would naturally fall 
about the Vicksburgian horizon, or lower Oligocene, but if it is posi- 
tively below the Gatun or Vamos 4 Vamos beds it cannot be newer than 
the Lower Claiborne Eocene. Тһе Foraminiferal fauna would fall in 
much more naturally above the fauna of the Gatun beds, and I should 
suspect a fault or overturn unless an inferior contact was actually 
observed. 
C. Vamos á Vamos or Gatun beds. From the number of species com- 
mon to this series and the Claiborne sands, as well as the Upper Tejon 
of California, there seems no escape from regarding this horizon (Nos. 18, 
19, 26) as Claibornian, or Upper Tejon, Eocene. The alternative that 
these beds range above the Vicksburgian seems decidedly less acceptable. 
In that case we should have to regard the species referred to as being 
unaccountable survivals. 
D. Mindi Hill beds. This is a deep water deposit, and may have 
been laid down in deep water at the same time that the Gatun beds 
were being formed nearer the shore. Тһе age is probably Claibornian 
Eocene (No. 4). 
E. Monkey Hill beds. — (Nos. 29, 48, 49, 87.) These are middle 
or upper Oligocene and agree with the so called Miocene of St. Domingo, 
Haiti, Trinidad, Curagoa, Jamaica, and the Chipola fauna of West 
Florida. "They contain a number of species in common with all these 
and with the Gatun beds, but by the loss of some of the more Eocene 
types and the acquisition of à number of modern forms are certainly 
1 Since this Report was submitted, Dr. Dall has published a paper containing 
notes on the collections described. See Descriptions of Tertiary Fossils from the 
Antillean Region, Proc. U. S. National Museum, Vol. XIX. pp. 308-391, 1890. 
