﻿GEOLOGY AND PALEONTOLOGY OF THE CANAL ZONE. 579 



also occurs in tho Oligocono of Antigua, and according to Doctor 

 MacDonald the Bohio underlies the Culebra formation, the lower 

 part of which seems to bo of middle Oligoccne age. However, tho 

 Bohio may be of middle Oligocene instead of lower Oligocene age. 



Romanes reports from Manzanilla, on the Pacific coast of Costa 

 Rica,^ a cherty rock in which tlicre are remains of Foraminifera, 

 including Gobigerina and "a complex form allied to Tinoporus," 

 which according to Dr. R. L. Sherlock is "most probably a species of 

 Orhiioides." As the so-called species of Tinoporus from Trinidad, 

 according to Douville, are referable to OriJiophragmina (Asierodiscus) , 

 it appears almost certain that the "form allied to Tinoporus" 

 mentioned by Romanes is a species of Asierodiscus. Dr. J. A. 

 Cushman has examined Romanes's figure, ^ based on a photomicro- 

 graph of a thin section of tho rock from Manzanilla, and writes mo 

 that it shows ^' OrJiojyhragmina and abundant Glohigerina, and that 

 the rock may be similar to that at David and on Haut Chagres." 

 The evidence is not entirely decisive, but tho probability is very strong 

 that the rock from Manzanilla, Costa Rica, is of lower Ohgoceno 

 (Lattorfian) age as is that at David and on Haut Chagres. It is 

 unfortunate that tho box containing Mr. Romanes's most important 

 specimens was lost in transit, but, notwithstanding this loss, he has 

 made a valuable addition to the literature on tho geology of Costa 

 Rica. 



Hill, in his description of a geologic section from San Jose, Costa 

 Rica, to tho coast at Port Limon, says: "At Guallava, the next 

 station oast of Las Animas, the Tertairy rocks are of Vicksburg age, 

 according to Dr. Dall." ^ On page 275 of Hill's paper. Doctor Dall 

 lists from this locality "the genuine Orhiioules manielli, PIios, Denial- 

 Hum, Plicaiula, Anomia, etc., all Vicksburg species." 



Between Costa Rica and Mexico there is no definite evidence as to 

 the presence or absence of lower OHgocene deposits, but as Sapper 

 mentions Nummuliies from Zacualpa, Yucatan, either Eocene or 

 Oligocene occurs at this place;* and, judging from the indefinite 

 statements of Sapper, deposits of cither Eocene or Oligocene age 

 underlie extensive areas in Chiapas and northern Guatemala.* 



Felix and Lenk " rQ.\iOTl .Nummuliies and "Orhiioides'' in northern 

 Chiapas, from collections made by Karstcn, and refer them to tho 

 Eocene, but sufficient data are not given to decide whether the 



> Romanes, J., Geolosy of a part of Costa Rica, Geol. Soc. LoaJon Quart. Joarn., vol. 68, pp. 130, 131, 

 pi. 9, fii;. 4, 1912. 



s Idem., pi. 9, fig. 4. 



» Hill, K. T., The geologic history of the Isthmus of Panama and portions of Costa Rica, Mas. Comp. 

 Zool. Bull., vol. 28, No. .5, p. 232, 1898. 



« Sapper, Carlos, La geographia fisica y la geologica dc la Peninsula do Yucatan, Mexico Inst. gcol. Bol. 

 3, p. 7, 1896. 



6 Petermann's Mittheil., Ergunzungs vol. 27, Ergiinzungshcft. 127, p. 67, 1899. 



'Felix, J., and Lenk, H., Ucber das Vorkommen von Nummulitenschichten in Mexico, NcucsJahrb. 

 fur M in. Jahrg. 1895, vol. 2, pp. 208-209, 1895. 



