HILL : GEOLOGY OF THE ISTHMUS OF PANAMA. 271 



PART VI. 



Appendices. 



Report by Dr. William H. Dall upon the Paleontology of 

 the Collections. 1 



I have examined the fossils from the Isthmus of Panama and Costa 

 Pica 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 Eocene. 



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 a Vamos beds it cannot be newer than 

 the Lower Claiborne Eocene. The 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 a Vamos or Gatun beds. From the number of species com- 

 mon to this series aud 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. The 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, Curacoa, 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 a 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. 303-331, 1896. 



