﻿548 BULLETIN 103, UNITED STATES NATIONAL MUSEUM. 



No. 6586c, near the mouth of Tonosi River, Doctor MacDonald col- 

 lected a species of Venericardia, on which Dr. C. W. Cooke makes the 

 following note: "A species of Venericardia from this locality is 

 scarcely distinguishable from a specimen labeled Venericardia plani- 

 costa var. horni from Cahborne, Alabama, but it does not closely 

 resemble specimens that I have seen from the Eocene of California, 

 Washington, and Oregon." According to Doctor MacDonald's de- 

 scription of the section, this species of Venericardia occurs 690 feet 

 below the bed in which Lepidocyclina panamensis Cushman and L. 

 duplicata Cushman were collected. I beheve that the latter bed 

 is the correlative of the lower part of the Culebra formation, as will 

 later be shown. Just below the Oligocene hmestone in which occur 

 the two species of Foraminifera mentioned are 650 feet of grayish, 

 well-beddea, rather fine-grained sandstone; this is underlain by 

 dark-gray, argiQaceous, fossihferous sandstone and shale, the latter 

 underlain by dark-gray, argillaceous sandstone, in which the speci- 

 mens of Venericardia were collected. 



Doctor MacDonald collected the plant Diospyros macdonaldi Berry 

 at station 65866, in grayish, argillaceous sandstone with some darker 

 shale beds, which immediately underlies the material in which the 

 species of Venericardia occurs. 



Dr. R. T. Jackson identifies as ScMzaster armiger W. B. Clark, an 

 echinoid collected by Mr. R. T. Hdl at BoniUa, Costa Rica. The type 

 of this species was obtained in a deposit of Jackson Eocene age at 

 Cocoa post office, Choctaw County, Alabama. It should be noted 

 that Mr. HiU says: "They [the rocks exposed] at BonHla Chff [Costa 

 Rica] are upper Oligocene, like the Monkey HUl beds."^ The deter- 

 mination of the Eocene age of this exposure is not positive. 



On page 197 of this volume, in my paper on the fossil corals, I 

 gave reasons for referring the typical part of the Brito formation of 

 Nicaragua, that part exposed near Brito, to the upper Eocene, and 

 correlated that part of the formation with the St. Bartholomew hme- 

 stone of the Island of St. Bartholomew and the Jacksonian upper 

 Eocene of the southeastern United States. The data and opinions 

 referred to need not be repeated. The presence in northern Colombia 

 of limestone containing small stellate OrthopJiragmina, indicating a 

 probable upper Eocene, was also noted on page 197. 



No fossil organisms were found in the Las Cascadas agglomerate 

 or the Bas Obispo formation. As they both underhe the Bohio con- 

 glomerate, which is of Oligocene, probably lower OHgocene age, they 

 are almost certainly of pre-OUgocene age. Although at present 

 information is not available for precisely determining their age, it 

 appears highly probable that they belong to the Eocene. However, 



' Hill, R. T., The geological history of the Isthmus of Panama and portions of Costa Rica: Mus. Comp. 

 Zool. Bull., vol. 28, p. 232, 1898. 



